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AP Biology
Saturday Study Session 3
Evolution as a Process
Student Packet
Session 1 – Microevolution
Multiple Choice Questions
1) During a study session about evolution, one of your fellow students remarks “ The giraffe stretched it’s
neck while reaching for higher leaves; it’s offspring inherited longer necks as a result.” Which statement
MOST accurately corrects the student’s misconception?
A)
B)
C)
D)
Spontaneous mutations can result in the appearance of new traits.
Only favorable adaptations have survival value.
Characteristics acquired during an organism’s life are not passed on through genes.
Disuse of an organ may lead to its eventual disappearance.
2) Inferences are conclusion statements that are reached on the basis of evidence and reasoning. All of the
following statements are inferences of natural selection. Which one is NOT an inference made by Charles
Darwin in developing his Theory of Natural Selection?
A) Subsequent generations of a population should have greater proportions of individuals that possess
favorable traits.
B) An individual organism undergoes evolution over the course of its lifetime.
C) Unequal reproductive success among its members leads to a population to adapt over time.
D) Often only a fraction of offspring survive because there is a struggle for limited resources.
3) Artificial selection is when humans interfere in natural processes and thereby affect the organism(s)
survival or ability to reproduce. One example is a farmer’s selecting the biggest and meatiest livestock to
reproduce in the hopes that the resulting offspring will be bigger and meatier. Which statement BEST
describes how artificial selection backfires in the evolution of pesticide resistance in a population of
insects?
A) Individual members of the population slowly adapt to the presence of the chemical by striving to meet
the new challenge.
B) All insects exposed to the insecticide begin to use a formerly silent gene to make a new enzyme that
breaks down the insecticide molecules.
C) Insects observe the behavior of other insects that survive pesticide application, and adjust their own
behaviors to copy those of the survivors.
D) A number of genetically resistant pesticide survivors reproduce. The next generation of insects
contains more genes from the survivors than it does from those killed by the insecticide.
4) Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones,
these bones having developed from the same embryonic tissues. How do evolutionary biologists interpret
these similarities?
A)
B)
C)
D)
By identifying the bones as being homologous structures that support common ancestry among them.
By identifying the bones as being analogous structures that support common ancestry among them.
As a fact of common coincidence and nothing more than that.
While the structures may be homologous in function, they do not convey any support for common
ancestry among the organisms as they live in different environments.
5) North American flying squirrels can be found at night gliding among the tree-tops gathering insects for
food. The Australian Sugar glider essentially leads the same lifestyle. If they were placed side by side, they
would look essentially the same; except one is a marsupial mammal and the other is not. How is it that
organisms thousands of miles apart could look identical?
A) These organisms are displaying adaptive radiation over time. When Pangaea broke apart, they moved
away from each other (radiated) and adapted to the different climates, which must be similar.
B) This is an example of convergent evolution. The two species appear to be one, but are not, simply
because they have evolved in similar environments and thereby similar traits are favored for survival.
C) They have undergone sympatric speciation. These two different species evolved during Pangaea, as a
result of competitive exclusion for resources.
D) These two species share a distant common ancestor. The process of anagenesis forced them to evolve
into two different species over time.
6) Given a population that contains genetic variation, what is the correct sequence of the following events,
under the influence of natural selection?
1.
2.
3.
4.
Differential reproductive success takes place.
A new selective pressure occurs within the environment.
Allele frequencies within the population change over time.
Environmental change occurs within an area.
A)
B)
C)
D)
2, 4, 1, 3
4, 1, 2, 3
4, 2, 1, 3
4, 2, 3, 1
Math Grid-In
In humans, there exists a rare genetic condition known as polydactyly (an extra digits). This autosomal dominant
genetic condition is associated with a base pair mutation within a Hox gene known as Sonic Hedgehog (SHH). This
gene is associated with embryonic development of the limb buds. It has an estimated prevalence of 34 out of
100,000. What is the allele frequency for the dominant allele (P) within humans based upon this information and a
theoretical population of 100,000? Round your answer to the nearest ten thousandth.
Short Free Response
1) Genetic Drift is referred to as a random change in allele frequency as a result of some event within a given
population. There exists two types of genetic drift that can occur – Bottleneck Effect and Founder Effect.
For each explain what is meant by the type of genetic drift and provide one example of how each might
occur.
2) Variation is key to surviving a changing environment. The ultimate source of the variation must be within
the genetic nucleotide sequence of gametes to be passed on to future generations. Describe three possible
processes that occur during sexual reproduction to increase genetic variation among a species population.
Long Free Response
Scientists use the concept of homology in identifying evolutionary relationships among organisms.
Features shared by two groups of organisms are said to be homologous if the similarities reflect shared
ancestry. Homology is found in comparisons of structural, molecular, biochemical, developmental,
physiological, and behavioral characteristics of organisms. Select THREE of the following hypotheses and
explain TWO examples of homology that support each hypothesis.
. (a) Chloroplasts are related to photosynthetic prokaryotes.
. (b) Spiders and insects are closely related.
. (c) Echinoderms (sea stars and their relatives) are closely related to the chordates (the phylum
that includes vertebrates).
. (d) Reptiles and birds are closely related.
. (e) Humans and chimpanzees are closely related primates