BIOL 226 EXAM UPDATED ACTUAL Questions and CORRECT
Answers
What facts would you use to explain to a creationist that · The fossil record shows us the evolution of organisms through time through
evolution is an historical fact? mineralized remains of organisms.
· The DNA record shows us how similar the genetic code for all life forms is and is
consistent with the fossil record.
· Direct observation shows us that organisms always match their environment, and
they can thank evolution for that.
· Vestigial structures show us historical remnants that use to serve a purpose in
organisms' ancestors. An example is the dorsal leg on a whale that is now
rendered useless but tells us that it once was useful and that whales evolved from
something with legs.
· Homologous structures show us similar structures are in different organisms who
share a common ancestor. These structures have different functions in all these
organisms.
· Analogous structures or convergent evolution shows us different structures that
have a similar function in different organisms. These structures have been inherited
separately in these organisms and have not come from a common ancestor.
Why is it crucial to construct evolutionary trees based on It is crucial to construct evolutionary trees based on homologies because they
homologies rather than analogies (convergent come from common ancestors, whereas analogies are separately inherited in
evolution)? unrelated organisms. If we tried to construct it based on analogies, then we would
have a messy tree of unrelated organisms which does not showcase the evolution
that has taken place.
Explain how Darwin used artificial selection as part of his He said that we can create many new variations through artificial selection (based
argument about the power of natural selection. on what we deem to be desirable traits) very easily, like when we took a wild
mustard plant to create broccoli and cabbage, we altered organisms to our
needs. Natural selection works in a similar way, except nature makes the decisions
of what is desirable for what context. (i.e., the landscape, the available resources,
the prey and predators, the weather, etc.)
Natural selection is an editing process rather than a Natural selection does not just create new species out of thin air with new
creative process. Explain by using an example. Your adaptations that allow them to survive and reproduce more successfully. Rather,
answer should be 2-3 sentences long. the desirable traits exist within variations of the same species. What natural
selection does is that it edits the species by allowing the organisms within the
species with undesirable traits to die off, while the one's with desirable traits
survive and reproduce more. Eventually, this gives rise to evolution and the
population is populated with mostly that desirable trait. This is what is important to
note about natural selection and evolution. Variation within the species is
necessary for evolution to take place. Natural selection is always at work. What is
a desirable trait now in a given species may not have been desirable generations
ago and maybe will not be desirable generations later.
, 3 modes on natural selection · Directional Selection: is a mode of natural selection in which one extreme
phenotype is favored over other phenotypes, causing the allele frequency to shift
over time in the direction of that phenotype
· Disruptive Selection: describes changes in population genetics in which both
extreme values for a trait are favored over intermediate values.
· Stabilizing Selection: where the intermediate phenotype is favored over the two
extremes.
Which of the five mechanisms cause the most Natural selection, gene flow, and genetic drift.
evolutionary change at the microevolutionary scale?
Why is genetic drift important for conservation biology? Endangered species are the "narrow" portion of a genetic bottleneck (reduced
genetic variation, less able to adapt to change).
The size of the population affects the strength of each 1. Natural selection (effect of population size: stays the same)
mechanism
2. Mutation (effect of population size: more mutations per generation in big
populations)
3. Drift (effect of population size: weaker in big populations)
4. Gene flow (effect of population size: weaker when population is large)
5. Non-random mating (effect of population size: stays the same)
Hardy Weinberg Theorem Assumption With this theorem, we are assuming that there will be the same number of
offspring, no mutation, no gene flow, will happen in a large population, and
random mating.
What does it mean if a population if different from Hardy This means that 1 of the 5 evolutionary mechanisms must be at work.
Weinberg?
Why do we care about the Hardy-Weinberg Theorem? Hardy Weinberg states that it is not enough to have variation to have evolution;
the frequencies of alleles and genotypes in a population will remain constant
unless acted upon by outside forces.
Why is geographic isolation so important for speciation? · Keeps the gene pool separate (Gene flow is the "enemy" of the local adaptation
& speciation)
· Allows populations to diverge due to: selection, drift, mutation, and assortative
mating
What happens if populations come back into contact 1. Geographic barrier
after separation? 2. Period of isolation
3. Re-contact
4. Either renewed gene flow or reproductive isolation
Answers
What facts would you use to explain to a creationist that · The fossil record shows us the evolution of organisms through time through
evolution is an historical fact? mineralized remains of organisms.
· The DNA record shows us how similar the genetic code for all life forms is and is
consistent with the fossil record.
· Direct observation shows us that organisms always match their environment, and
they can thank evolution for that.
· Vestigial structures show us historical remnants that use to serve a purpose in
organisms' ancestors. An example is the dorsal leg on a whale that is now
rendered useless but tells us that it once was useful and that whales evolved from
something with legs.
· Homologous structures show us similar structures are in different organisms who
share a common ancestor. These structures have different functions in all these
organisms.
· Analogous structures or convergent evolution shows us different structures that
have a similar function in different organisms. These structures have been inherited
separately in these organisms and have not come from a common ancestor.
Why is it crucial to construct evolutionary trees based on It is crucial to construct evolutionary trees based on homologies because they
homologies rather than analogies (convergent come from common ancestors, whereas analogies are separately inherited in
evolution)? unrelated organisms. If we tried to construct it based on analogies, then we would
have a messy tree of unrelated organisms which does not showcase the evolution
that has taken place.
Explain how Darwin used artificial selection as part of his He said that we can create many new variations through artificial selection (based
argument about the power of natural selection. on what we deem to be desirable traits) very easily, like when we took a wild
mustard plant to create broccoli and cabbage, we altered organisms to our
needs. Natural selection works in a similar way, except nature makes the decisions
of what is desirable for what context. (i.e., the landscape, the available resources,
the prey and predators, the weather, etc.)
Natural selection is an editing process rather than a Natural selection does not just create new species out of thin air with new
creative process. Explain by using an example. Your adaptations that allow them to survive and reproduce more successfully. Rather,
answer should be 2-3 sentences long. the desirable traits exist within variations of the same species. What natural
selection does is that it edits the species by allowing the organisms within the
species with undesirable traits to die off, while the one's with desirable traits
survive and reproduce more. Eventually, this gives rise to evolution and the
population is populated with mostly that desirable trait. This is what is important to
note about natural selection and evolution. Variation within the species is
necessary for evolution to take place. Natural selection is always at work. What is
a desirable trait now in a given species may not have been desirable generations
ago and maybe will not be desirable generations later.
, 3 modes on natural selection · Directional Selection: is a mode of natural selection in which one extreme
phenotype is favored over other phenotypes, causing the allele frequency to shift
over time in the direction of that phenotype
· Disruptive Selection: describes changes in population genetics in which both
extreme values for a trait are favored over intermediate values.
· Stabilizing Selection: where the intermediate phenotype is favored over the two
extremes.
Which of the five mechanisms cause the most Natural selection, gene flow, and genetic drift.
evolutionary change at the microevolutionary scale?
Why is genetic drift important for conservation biology? Endangered species are the "narrow" portion of a genetic bottleneck (reduced
genetic variation, less able to adapt to change).
The size of the population affects the strength of each 1. Natural selection (effect of population size: stays the same)
mechanism
2. Mutation (effect of population size: more mutations per generation in big
populations)
3. Drift (effect of population size: weaker in big populations)
4. Gene flow (effect of population size: weaker when population is large)
5. Non-random mating (effect of population size: stays the same)
Hardy Weinberg Theorem Assumption With this theorem, we are assuming that there will be the same number of
offspring, no mutation, no gene flow, will happen in a large population, and
random mating.
What does it mean if a population if different from Hardy This means that 1 of the 5 evolutionary mechanisms must be at work.
Weinberg?
Why do we care about the Hardy-Weinberg Theorem? Hardy Weinberg states that it is not enough to have variation to have evolution;
the frequencies of alleles and genotypes in a population will remain constant
unless acted upon by outside forces.
Why is geographic isolation so important for speciation? · Keeps the gene pool separate (Gene flow is the "enemy" of the local adaptation
& speciation)
· Allows populations to diverge due to: selection, drift, mutation, and assortative
mating
What happens if populations come back into contact 1. Geographic barrier
after separation? 2. Period of isolation
3. Re-contact
4. Either renewed gene flow or reproductive isolation
