Download 4-26-13 Unit 7 (Evolution) Review

Evolution Review
1. What is a scientific theory?
A scientific theory is an explanation that explains HOW AND WHY something occurs and is supported
by ALL OF THE EVIDENCE AVAILABLE.
2. What is evolution?
A scientific theory that states that living species are descendants of ancestral species that were
different from present day ones (the genetic changes in a population over generations)
3. Evolution occurs in (populations / individuals)? (Circle which one is correct)
4. Charles Darwin had two main themes that made up his theory of evolution. What are
they and what does each of them mean?
1. _Descent with modification______________ - Basically, this says that all living
things come from something living before them (biogenesis) and have become
modified (or changed) from their ancestor
2. __Survival of the fittest____ - The process by which organisms best suited to the
environment survive, reproduce, and pass their genes to the next generation.
Occurs in populations, not in individuals
5. In evolutionary terms, what is fitness?
Fitness -(1) Survive Longer, (2) Reproduce More
(3) Pass on traits to next generation
Note: It is not essential to survive longer. The longer life simply gives more time to produce
more offspring. Ex. Evolution would favor someone who was 20 and had 4 kids rather than
someone who is 80 with 1 kid.
6. What is a mutation?
MUTATION: a change in a gene
Remember that a gene is enough DNA to control 1 trait
7. What are the two types of mutations? (In your description, tell if the mutation DOES / DOES NOT
affect the PARENT ORGANISM and the OFFSPRING)
(1) Changes in genes in somatic (body) cells: can affect the organism itself, but cannot be passed to
sexually produced offspring.
(2) Changes in genes in gametes (egg and sperm): do not affect the parent organism itself, can
be passed to sexually produced offspring
8. How often do mutations occur?
Rarely
On the rare occasion when mutations produce favorable traits, a population’s gene pool (all of the
genes in a population) is changed because of the introduction of this new, favored trait. The
population will then evolve through natural selection to show a greater percentage of the new,
beneficial trait.
9. Refer to question 8 for this answer. Because mutations occur _rarely_______________, evolution
occurs __slowly______________.
*** This is generally true, but there are times when evolution can occur RAPIDLY (in evolutionary time
anyway…rapidly would be in a couple thousand years).
10. Who is Jean Baptiste Lamarck?
Like Darwin, he also believed populations change over time
BUT, his beliefs are no longer supported
Lamarck’s ideas on evolution:
Believed in Spontaneous Generation
Simple forms of life eventually develop into more complex forms
Traits gained in life by experience or behavior could be passed on to offspring
(Ex. Bodybuilder parents
Bodybuilder baby)
12. Define coevolution and provide an example of it.
When two or more species have evolved together, the situation is called coevolution.
Example:Insects and Flowers
Flowers provide food for insects. Insects take pollen from one flower to the next so they can
reproduce.
13. Define convergent evolution and tell what causes it.
Convergent evolution – process by which different species evolve similar traits
(SAME FUNCTION, DIFFERENT ANCESTOR)
Example: Birds, bats, and moths have wings, but they did not evolve from a recent common
ancestor.

Caused by:
◦
living in similar habitats / performing similar functions
14. Define divergent evolution and tell what causes it.
Divergent evolution- build up of differences between groups which can lead to the development of a
new species
In other words, two different species that evolved from the same ancestor.
Caused by populations of the same species:
moving to two different environments or specializing in different areas of the same environment
14. What are analogous structures?
Structures with closely related function but do not come from the same ancestral structure
Same function, different structure
Example: Birds, bats, and moths have wings, but they did not evolve from each other.
15. Analogous structures are caused by what kind of evolution?
Convergent (things starting to look alike but they’re not really related)
16. What are homologous structures?
Structures in different species that originated from common ancestor
May have different function but similar structure
17. Homologous structures are caused by what kind of evolution? Divergent (things that are related but
start to look different over time)
18. Define vestigial structures and give an example of them.
No longer have a use, but may have had a use in evolutionary history.
Ex. Appendix, ear muscles
19. How old does the fossil record tell us the Earth is? 4.5 billion years old (the oldest living thing was
about 3.5 billion years)
20. How do fossils provide evidence for evolution? We can see the change in a population over time
through the fossils; Can also use relative dating (strata) and absolute dating (carbon dating in fossils)
to see what time period the species were alive
21. The Earth is divided into layers. The layers on top are (younger / older) making the layers toward the
bottom (younger / older).
22. Draw a graph showing the three types of natural selection. Label and explain what is happening in
each graph.
 Stabilizing
Selection against the extreme phenotypes (physical type)
This causes average phenotype to become much more common (the look of the population is very
similar and average)
Ex. Human weight at birth
 Directional Selection
favors one extreme phenotype (physical type)
This causes this particular extreme phenotype to become much more common (the look of the
population is pushed in 1 direction)
Ex. Peppered Moths
 Disruptive
Selection that favors both extreme phenotypes (physical type)
This causes extreme phenotypes to become much more common (the look of the population shows
extreme differences)
Ex. Darwin’s Finches
23. Explain how the following scientists contributed to the theory of spontaneous generation, including
the experiments they performed.
 Redi – Did experiment showing that maggots come from flies and not from meet
o Remember: Redi = Red meat

Needham- Tried to PROVE spontaneous generation (only guy who did that)
o Boiled broth in a flask and WAITED TO COVER IT UP until after it had cooled (that was
the problem with his experiment)
o bacteria entered flask as it cooled
o Saw bacteria return to flask
o Thought this proved spontaneous generation
 Remember = Needham “needs” to get a better experiment

Spallanzani – Did basically the same experiment as Needham but was trying to disprove
spontaneous generation
o Difference was that he covered up the flask immediately so no bacteria came back
o People argued that he killed the “life force” of the air so they didn’t accept his results

Pasteur – Did same experiment as Needham and Spallanzani but came up with a flask that
allowed AIR TO ENTER BUT BACTERIA COULD NOT
o This set up would’ve allowed the “life force” of the air to reenter
o Still, there were no bacteria that returned to the flask
o Proved biogenesis to be true (and spontaneous generation to be false) once and for all
24. Explain Miller and Urey’s experiment and their findings.

Did experiment trying to show how the first cells could have been formed (Lightning
experiment)
25. How did Lyell contribute to Darwin’s evolution theory?

Said that geologic change takes LONG PERIODS OF TIME; Darwin took that to mean that
Biological change (evolution) would also occur over extremely long periods of time
26. How can an amino acid sequence (molecular biology) be used to tell if two organisms are related?
The closer 2 different species DNA is to one another, then the closer those 2 are related.
All living things use DNA and RNA.
The genetic code amongst all living things is universally the same. (In other words, the fact that the
RNA codon AUG gives the amino acid MET in humans is seen in every other living thing as well)
27. After the mass extinction of dinosaurs, mammals diversified rapidly. This is an example
of
adaptive radiation
.
28. If 2 animals are the same species, then they are able to do what together?
Make fertile offspring (make babies that can make babies)