NR602 Midterm Exam Study Guide, Verified Questions with
Correct Answers and Detailed Rationales (A+ Rated) 2026/2027
What was the primary cause behind Darwin's finches developing into different
subspecies?
(a) Droughts
(b) Competition for resources
(c) Different microclimates of each island
(d) Selective mating
(e) None of the above
Correct Answer: C) Each kind of finch has a different beak because natural selection
has selected for the beak that optimizes the most abundant food source in the particular
climate that the specific birds live in. Because each of the Galapagos islands had such
different microclimates, the same finches were able to develop differently, making it a
perfect location for Darwin to study natural selection without far travel.
Which of the following is true of pre-Darwin beliefs about evolution?
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,(a) Organisms could modify features over their lifetime and these acquired traits could
be passed genetically to offspring
(b) Organisms could modify features over their lifetime but these traits would not be
passed genetically to their offspring
(c) The ideas that perpetuated before Darwin's concept of evolution have been
completely discredited
(d) Both A and C
(e) Both B and C
Correct Answer: A) For instance, this belief, largely perpetuated by Lamark, was said
to act on giraffe's necks. The giraffe's were able to grow longer necks by stretching to
get to taller leaves, and through this growth, they were able to pass on the trait of longer
necks to their offspring. In reality, the giraffe's with longer necks were simply surviving
better due to the ability to get more food, thus they passed on their genes more.
However, this theory is not completely discredited because there are certain traits that
our own actions can cause to be expressed differently. For instance, skin tone due to
melanin is very dependent on how much time a person spends outside in the sun. This
is now known as the field of ethogenetics, and while it cannot pass on traits acquired
over the lifetime to offspring, we do see variations of traits based on our own actions,
thus not completely discrediting Lamark's ideas.
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,Which of the following is NOT a factor that prevents selection from reducing to a single
favorable allele?
(a) Environmental Variation- different environments making different features favorable
(b) Selective Mating- specific traits being more attractive to the opposite gender
(c) Heterozygote Superiority- heterozygotes sometimes having more advantages than
homozygotes
(d) Frequency dependent selection- fitness depending on how common a phenotype is
in the population
(e) Mutation- new alleles arising through random mutation
Correct Answer: B) Selective mating, certain traits being more favorable to the
opposite gender (ex. a bird's song being more complex, a peacock's feathers being
bright) would encourage selection for one specific trait, which would encourage
reducing the allele to a single favorable one (barring complications from costly
signaling). The other choices are talked about in Chapter 1 G&McB.
Which of the following traits of adaptation describes a trait that would increase the
fitness of neighbors but decrease the fitness of yourself?
(a) Selfish trait
(b) Altruistic trait
(c) Cooperative trait
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, (d) Spiteful trait
(e) None of the above
Correct Answer: B) Selfish- increase your own fitness while decreasing neighbors,
altruistic- increase neighbor's fitness while decreasing your own, cooperative- increase
both your own and your neighbor's fitness, spiteful- decreasing both your own and your
neighbor's fitness. Traits explained more in G&McB chapter 2.
Which of the following is an example of a vestigial organ?
(a) A kiwi's wings
(b) A whale's hind leg bones
(c) A human tailbone
(d) Both B and C
(e) All of the above
Correct Answer: E) A vestigial organ is a structure or organ that used to be functional
in the ancestors of a species but over time have evolved to be useless. Therefore, a
flightless bird doesn't actually need their wings, whale's don't have legs and don't need
leg bones, and humans don't have tails but still have tailbones.
It was originally theorized that evolutionary changes took place over periods of
hundreds of years, there is now evidence that it happens ______________
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