Download Evolution Test Review

Evolution Test Review
1. Give a definition for evolution. Why
do living things need to evolve?
• Definition: living things changing over time by
which descendants come to differ from
ancestors.
• As the environment changes, living things
need to survive, so they too must change as
time goes on.
2. How are fossils dated?
• Radiometric/ Radiocarbon Dating: measures the
amount of radioactive isotopes in a fossil to
determine its age
– Pro: can give you the exact age of a fossil
– Con: can’t be used on really old fossils because the
radioactivity goes away with time
• Relative Dating: compares the age of a fossil to
other fossils found in the same rock layer
– Pro: can be used to give you an estimated age of really
old fossils
– Con: rock layers can be shifted by earthquakes or
mudslides and this can give an inaccurate estimate
3. How can we get evidence for
evolution from the fossil record?
• The fossil record shows us how living things
have changed their forms over time
4. What are homologous structures?
Give an example. How do they
provide evidence for evolution?
• Similar structures with different functions
• Example: a human’s arm and a bat’s wing
• Evidence: they show that there was a common
ancestor
5. What are vestigial structures? Give
an example. How do they provide
evidence for evolution?
• Structures that no longer serve a purpose but
had a purpose in an ancestor
• Example: Appendix & tailbone in humans;
wings on flightless birds
• Evidence: show how things change over time,
gives evidence of a common ancestor (i.e.
wings on both flightless birds and regular birds
point to a common ancestor).
6. How does embryology (study of
embryos/development) provide
evidence for evolution?
• Similarities among embryos show a common
ancestor
• Also show how things have changed over time
(ex – human embryos have gill slits and tails as
embryos that go away during development)
7. What molecular evidence can be
used to support the theory of
evolution? Why does it support the
theory?
• Similar DNA sequences and proteins
• The more close the DNA sequences and
proteins are, it is thought that the more
closely related the two species will be
• Shows evidence of a common ancestor
8. How does biogeography provide
evidence for evolution?
• It shows that island species have a lot of
similarities to animals on the closest mainland
• It shows how species have adapted for the
environment that they live in, but also must
have evolved from a common ancestor
9. Explain Charles Darwin’s discoveries
(finches and tortoises).
• Finches:
– Darwin noticed that where there were nuts for
food, the finches had short, hard beaks
– Where there was fruit and insects for food, the
finches had long, thin beaks
• Tortoises:
– Darwin noticed that where there was low
vegetation, the tortoises had short legs and necks
– where there was high vegetation, the tortoises
had long legs and necks
10. What are adaptations? Give an
example of an adaptation
• Adaptation: a beneficial change that allows an
organism/species to better survive in its
environment compared to those that don’t
have that version of the trait.
• Example: thick fur on a rabbit that lives in the
arctic
11. What 3 things can we learn by
studying cladograms?
• Cladograms show:
– Probable relationships
– Probable sequence of organisms (which organisms
evolved first).
– Shared derived characters (which species share
certain heritable traits)
12. How do you read a cladogram?
• Reads from the bottom up
– Oldest/most common trait at the bottom
– Newest/least common trait at the top
• Each organism on the cladogram has all the
traits below it
13. Describe survival of the fittest.
• The best adapted to the environment will
survive and leave offspring behind to continue
the species
• Example: the fastest running prey will be able
to avoid predators and survive better than
slower prey
14. What is the purpose of sexual
selection?
• Gives males traits to attract the best females
to mate with. Males with these traits pass
their alleles on more to the next generation.
• This allows the species to better survive (more
offspring)
15. Describe extinction (include
background and mass). Why do
species become extinct?
• Background: happens over longer time
periods at a slow rate
• Mass: happens suddenly and drastically
(wipes out lots of species on a global level)
• Species become extinct because they lack the
variations needed to survive in the new
environment
16. Describe genetic drift. Include the
bottleneck effect and founder effect.
• Genetic drift: changes in the alleles of a
population due to chance
• Bottleneck effect: occurs when a “bottleneck
event” (ex – natural disaster) drastically reduces
the population so that it no longer resembles the
original population
• Founder effect: occurs when part of a
populations colonizes a new area and may evolve
into a new species
17. What is gene flow?
• Movement of alleles between populations
– Example: migration
– Lack of gene flow between populations may lead
the two populations to evolve into different
species.
18. What does it mean to be
biologically fit?
• It means that the individuals are able to
survive and reproduce
19. What are variations? Give an
example.
• Differences in a certain trait in a population
• Example: different beak types in finches
• Source: Random mutations & Recombination
(crossing over & independent assortment
during meiosis)
20. What is a gene pool?
• All the alleles of a gene available to a
population
21. What are allele frequencies?
• How often certain alleles are seen in a
population
• They can tell you which alleles better help a
population survive (a more common allele
would be thought to be more beneficial)
• Beneficial alleles should increase in frequency,
detrimental alleles should decrease in
frequency.
22. What is natural selection?
• Organisms will inherit beneficial adaptations
that will help them survive and leave behind
more offspring than other individuals without
those adaptations.
23. What is reproductive isolation? Describe the
3 isolating mechanisms and how they lead to
speciation.
• Reproductive isolation is when members of different
populations can no longer mate successfully with
one another-final step before speciation (when two
or more species arise from one existing species) due
to no gene flow. This may occur due to:
– Behavioral isolation: differences in courtship
behaviors between populations
– Geographic isolation: physical barriers separate
populations
– Temporal isolation: timing of mating prevents
reproduction between population
24. Describe directional, stabilizing, and
disruptive selection. Give examples.
• Directional: favors phenotype at one extreme
– Example: bacteria that are resistant to antibiotics will survive and
shift the population to all (mostly) have that same trait
• Stabilizing: favors the intermediate phenotype
– Example: gall flies lay their eggs in plants and that creates a “gall”
in the plant – the medium sized galls are left alone while the small
galls are destroyed by wasps and the large galls are destroyed by
woodpeckers
• Disruptive: favors both extreme phenotypes
– Example: bright blue (dominant trait) male buntings (birds) will
attack and kill blue-brown (intermediate pheno.) males and leave
the brown (recessive) males alone