Download Evolution Key

Name ________________________
Period ________
Evolution Test Review
DUE
2/
/16
1) A group of interbreeding organisms (a species) living in a given area is called
__population___
2) Give an example of a species. Ex. One wolf
Give an example of a population. Ex. Pack of wolves in the prairie
3) Combined (sum total) genetic material of all the members of a population is called __ Gene
Pool__. Ex. genes of all the tuna in the gulf.
4) If you have 20 blue M&Ms and a total of 40 M&Ms, what is the allele frequency of the blue
ones?
Show work! 20 blue/40 total = 2/4  ½  50%
5) What do the big T and little t represent in the Tt genotype? Alleles (versions) of a gene
6) The number of each allele for a trait as a fraction of all the alleles for a particular trait is called Allele
frequency
7) Evolution is the change in the gene pool (allele frequency changes) of a population (population or
individual) over time.
8) What are the conditions of Genetic Equilibrium (stable allele frequency)?
Large population-no migration – random mating-no natural selection-no mutations
9) What factors lead to evolution (change) in a population?
Migration, natural selection, mutation, nonrandom mating, small population size (selective)
10) Does a small or large population have a better chance of survival during environmental changes?
Why? A large population – because they have more variation.
11) What is variation? Differences in a trait in a population
12) What is biodiversity? How much variation a population has.
What benefit does it have on population? It is better for a population to have a high biodiversity in case of
the environmental changes – it increases a population’s survival.
13) Explain how each of the following sources contributes to the variation of a population.
i) Crossing Over – responsible for the majority of variation. Chromatids tangle, exchange pieces and
separate. This leads to different combination of genes on chromosomes.
ii) Sexual reproduction – each gamete carry different versions of the alleles from each parent 
different genetic make-up.
iii) Mutations – only source of new (spontaneous) variation in a gene pool
iv) Independent Assortment – No two gametes will have the same exact genetic combination
v) Random Joining of Gametes – there are various possibilities when eggs and sperm join.
Contributes to gene diversity in the zygote.
vi) Outbreeding – increases the possibility of mixing different alleles and creating new allele
combinations.
14) What can happen if 1 species is separated for long periods of time and come into contact with different
environmental conditions? It could respond differently to selective pressures
What effect does this have on the species? It can eventually become different species.
This phenomenon above is called speciation.
Provide an example of speciation. Ex. Abert squirrels separated by Grand Canyon.
15) What is Natural Selection? Survival of the fittest – those organisms with more adaptive (favorable) traits have a
better chance to survive and reproduce - has a selective advantage (leaves a gene pool better fit).
Natural selection occurs at which level, population or individual? Population
Give an example of natural selection in action. Ex. Some populations of dogs have short hair and other long hair.
When temperature drops, the long haired ones will survive longer and pass on their genes while the short hair ones
die off.
16) What are adaptations? Give examples. Traits that help an organism survive and reproduce. Ex. Wings,
claws, teeth. Camouflage, venom, speed, mimicry, etc.
17) Compare Darwin’s hypothesis to Lamarck’s.


Lamarck – thought individual organism changed (evolved). Environment creates a need for a certain features to
be developed in order to survive. Acquired (developed) characteristics are inheritable  not true.
Darwin – thought all genetic variations were in the population regardless of organism’s needs. Variation is
inherited – passed on to offspring. He believed in evolution by Natural Selection - The best fit survived and
reproduced – the one with more adaptive traits. Environment “screens out” or SELECTS) features contributing to
survival.
Who do we believe has more evidence to support his theories? Darwin.
18) Do individual organisms or populations evolve? Populations; Gene pools in a population change over time.
19) When the finches were separated on different islands, how did they adapt to their environment?
Different beak size
What was the result? Speciation
What caused the changes in the beak size? Natural Selection
20) What are the three different types of natural selection and what does each type select for (favor)?
 Stabilizing selection – selects for (favors) individuals with intermediate phenotypes (eliminates
extremes) – population looks more similar over time
 Directional selection – select for (favors) individuals at one extreme. Population looks different over
time
 Disruptive selection – select for (favors) individuals at both ends (both extreme phenotypes) –
populations split into two groups
21) If you found two fossils in two different layers of sedimentary rock stacked
on each other, how would you know which one is older? How can you know
for sure? The fossil from the deeper layer would be older because that layer
of rock had to be laid there first before the other layer.
22) Looking at the structures of organisms, how can you tell if two organisms
are believed to have evolved from a common ancestor?
If the structures are homologous, then you can assume that they share a common ancestor.
23) When scientists are constructing evolutionary relationships, why do they primarily utilize DNA?
Shared or identical sequences of DNA give hard proof of common ancestry, whereas shared traits or similar
characteristics can be the result of convergent evolution.
24) What is genetic drift? A random change in allele frequency – most common in small populations.
What effect does it have on the variation of a population? Decrease in a genetic diversity b/c a population
is descended from a small number of colonizing ancestors.
What is a bottleneck effect? It is a genetic drift that occurs after a bottleneck event (ex. Earthquakes,
volcano eruption)  an event drastically reduces population size.
What is a Founder effect? When a few individuals start a new population may lead to speciation.
25) What is a gene flow? Exchange of genes between populations.
What does “alleles immigrate” mean? Alleles coming in (added) a gene pool
What does “alleles emigrate” mean? Alleles moving out (lost) of a gene pool
26) Use the phylogenic tree to answer the following questions.
a) Which organisms are most closely related? B and C
b) Which organism(s) are least related to C? D
c) Which letter represents the most recent common ancestor of B and C? X
Answer the following questions using the choices provided.
A. Homologous Structure
B. Analogous Structure
C. Vestigial Structure
D. Molecular/Biochemical Evidence
E.
F.
G.
H.
Fossil Evidence
Embryological Evidence
Biogeographical Evidence
Coevolution
1. Anatomically similar structures but have different functions. _____A______
Would this be an example of divergent or convergent evolution? Divergent
2. In the earliest stages of development, a tail and gill slits can be seen in rabbits,
fish, birds and humans. ____F___
3. Exemplified by forelimbs of birds, whales, pigs, and monkeys. ____A_____
4. The forelimbs of flightless birds. _____C______
5. DNA and RNA comparisons may lead to evolutionary trees or cladograms.
____D______
6. Bird and Butterfly wings have same function but different structures. _____B______.
Would this be an example of divergent or divergent evolution? Convergent
7. A body structure no longer used but may have had a function in an early ancestor. Ex.
Tail bone in humans; Wings in an ostrich____C_______
8. Geographic Isolation would fit into this category. _____G_________
9. Organisms that have changed over time and have become so adapted to each other that they no longer survive
without each other. ____ H_____
10. Moth feeds exclusively on the orchid, and the orchid’s pollen is spread by the moth. This scenario is an example
of ______ H ____