TAMU BIOLOGY 112 STUDY GUIDE 2025/2026 QUESTIONS
WITH ANSWERS RATED A+
✔✔Two populations of birds with somewhat different coloration live on opposite sides of
a peninsula. The habitat between the populations is not suitable for these birds. When
birds from the two populations are brought together, they produce young whose
appearance is intermediate between the two parents. These offspring will breed with
each other or with birds from either parent population, and all offspring of these pairings
appear intermediate to various degrees.
What keeps the 2 populations separate?
A) Behavioral reproductive isolation
B) Temporal reproductive isolation
C) Habitat isolation
D) Lack of hybrid viability - ✔✔C) Habitat isolation
✔✔Three populations of crickets look very similar, but the males have courtship songs
that sound
different. What function would this difference in song likely serve if the populations came
in
contact?
A) a postzygotic isolating mechanisma
B) a temporal reproductive isolating mechanism
C) a behavioral reproductive isolating mechanism
D) gametic reproductive isolating mechanism - ✔✔C) a behavioral reproductive isolating
mechanism
✔✔The peppered moth provides a well-known example of natural selection. The light-
colored form of
the moth was predominant in England before the Industrial Revolution. In the mid-
nineteenth
century, a dark-colored form appeared. The difference is produced by a dominant allele
of one
gene. By about 1900, approximately 90% of the moths around industrial areas were
dark colored,
whereas light-colored moths were still abundant elsewhere. Apparently, birds could
readily find
the light moths against the soot-darkened background in industrial areas and, therefore,
were
eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the
landscape,
and the dark-colored moths have been disappearing. Should the two forms of moths be
considered
separate species?
A) Yes, because natural selection has affected the frequency of the two different forms.
B) Yes, because they are reproductively isolated based on habi - ✔✔D) No.
,✔✔Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J.
monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from
one species are unable to germinate and make pollen tubes on female ovules (which
contain egg cells) of the other species. These two juniper species are kept separate by
______.
A) behavioral isolation
B) gametic isolation
C) temporal isolation
D) habitat isolation - ✔✔B) gametic isolation
✔✔House finches were found only in western North America until 1939, when a few
individuals were released in New York City. These individuals established a breeding
population and gradually expanded their range. The western population also expanded
its range somewhat eastward, and the two populations have recently come in contact. If
the two forms were unable to interbreed when their expanding ranges meet, what would
this situation definitely illustrate?
A) reinforcement
B) allopatric speciation
C) sympatric speciation
D) prezygotic isolation - ✔✔B) allopatric speciation
✔✔If species "A" is 2n=6 and species "B" is 2n=4 were to interbreed and have a sterile
hybrid of 5 chromosomes yet later encounter a mitotic or meiotic error whereby the
diploid number is then 10 and then that organism becomes viable, this would be an
example of:
A) autopolyploidy
B) auxoploidy
C) agroploidy - ✔✔A) autopolyploidy
✔✔in domesticated dogs certain traits are selected for by the breeders. The unintended
consequence is that approximately 25% of all pure-bred dogs in the US now have some
neurological or sensory disorder. This is an example of:
A) artificial selection
B) sexual selection
C) kin selection
D) allopolyploid selection - ✔✔A) artificial selection
✔✔Which of the following is the correct sequence of these events in the origin of life?
I. Formation of protobionts
II. Synthesis of organic monomers
III. Synthesis of organic polymers
IV. formation of DNA-based genetic systems
A) II, III, IV, I
B) I, II, III, IV
, C) II, III, I, IV
D) I, III, II, IV - ✔✔C) II, III, I, IV
✔✔Which of the following is a defining characteristic that all protobionts had in
common?
A. the ability to synthesize enzymes
B. the ability to replicate RNA
C. a surrounding membrane or membrane-like structure
D. RNA genes - ✔✔C. a surrounding membrane or membrane-like structure
✔✔The first genetic material on Earth was probably ____.
A) DNA molecules whose information was transcribed to RNA and later translated in
polypeptides.
B) self-replicating RNA molecules
C) DNA produced by reverse transcriptase from abiotically produced RNA
D) oligopeptides located within protobionts - ✔✔B) self-replicating RNA molecules
✔✔Why are fossils so important in terms of evolutionary and biological study of the
planet Earth?
A) Fossils show us the forms of life that have gone extinct, but were clearly resident of
Earth at one point.
B) Fossils can be dated and thus the age (when it resided on this planet) of the
organism can be determined from the fossil.
C) In general, soft-bodied organisms only had to reside on the planet for a short period
of tie to become fossilized.
D) Both A and B.
E) Both A, B, and C. - ✔✔D) Both A and B.
✔✔Which of these observations give the most support to the endosymbiotic theory for
the origin of eukaryotic cells?
A) the similarity in size between the cytosolic ribosomes of prokaryotes and the
ribosomes within mitochondria and chloroplasts
B) the existence of structural and molecular differences between the plasma
membranes of prokaryotes and the internal membranes of mitochondria and
chloroplasts
C) the observation that some eukaryotic cells lack mitochondria
D) the size disparity between most prokaryotic cells and most eukaryotic cells - ✔✔A)
the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes
within mitochondria and chloroplasts
✔✔stanley miller's 1953 experiments supported the hypothesis that ________.
A) life on Earth arose from simple organic molecules, with energy from lightning and
volcanoes.
B) the conditions on early Earth were conducive to the origin of life.
WITH ANSWERS RATED A+
✔✔Two populations of birds with somewhat different coloration live on opposite sides of
a peninsula. The habitat between the populations is not suitable for these birds. When
birds from the two populations are brought together, they produce young whose
appearance is intermediate between the two parents. These offspring will breed with
each other or with birds from either parent population, and all offspring of these pairings
appear intermediate to various degrees.
What keeps the 2 populations separate?
A) Behavioral reproductive isolation
B) Temporal reproductive isolation
C) Habitat isolation
D) Lack of hybrid viability - ✔✔C) Habitat isolation
✔✔Three populations of crickets look very similar, but the males have courtship songs
that sound
different. What function would this difference in song likely serve if the populations came
in
contact?
A) a postzygotic isolating mechanisma
B) a temporal reproductive isolating mechanism
C) a behavioral reproductive isolating mechanism
D) gametic reproductive isolating mechanism - ✔✔C) a behavioral reproductive isolating
mechanism
✔✔The peppered moth provides a well-known example of natural selection. The light-
colored form of
the moth was predominant in England before the Industrial Revolution. In the mid-
nineteenth
century, a dark-colored form appeared. The difference is produced by a dominant allele
of one
gene. By about 1900, approximately 90% of the moths around industrial areas were
dark colored,
whereas light-colored moths were still abundant elsewhere. Apparently, birds could
readily find
the light moths against the soot-darkened background in industrial areas and, therefore,
were
eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the
landscape,
and the dark-colored moths have been disappearing. Should the two forms of moths be
considered
separate species?
A) Yes, because natural selection has affected the frequency of the two different forms.
B) Yes, because they are reproductively isolated based on habi - ✔✔D) No.
,✔✔Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J.
monosperma) have overlapping ranges. Pollen grains (which contain sperm cells) from
one species are unable to germinate and make pollen tubes on female ovules (which
contain egg cells) of the other species. These two juniper species are kept separate by
______.
A) behavioral isolation
B) gametic isolation
C) temporal isolation
D) habitat isolation - ✔✔B) gametic isolation
✔✔House finches were found only in western North America until 1939, when a few
individuals were released in New York City. These individuals established a breeding
population and gradually expanded their range. The western population also expanded
its range somewhat eastward, and the two populations have recently come in contact. If
the two forms were unable to interbreed when their expanding ranges meet, what would
this situation definitely illustrate?
A) reinforcement
B) allopatric speciation
C) sympatric speciation
D) prezygotic isolation - ✔✔B) allopatric speciation
✔✔If species "A" is 2n=6 and species "B" is 2n=4 were to interbreed and have a sterile
hybrid of 5 chromosomes yet later encounter a mitotic or meiotic error whereby the
diploid number is then 10 and then that organism becomes viable, this would be an
example of:
A) autopolyploidy
B) auxoploidy
C) agroploidy - ✔✔A) autopolyploidy
✔✔in domesticated dogs certain traits are selected for by the breeders. The unintended
consequence is that approximately 25% of all pure-bred dogs in the US now have some
neurological or sensory disorder. This is an example of:
A) artificial selection
B) sexual selection
C) kin selection
D) allopolyploid selection - ✔✔A) artificial selection
✔✔Which of the following is the correct sequence of these events in the origin of life?
I. Formation of protobionts
II. Synthesis of organic monomers
III. Synthesis of organic polymers
IV. formation of DNA-based genetic systems
A) II, III, IV, I
B) I, II, III, IV
, C) II, III, I, IV
D) I, III, II, IV - ✔✔C) II, III, I, IV
✔✔Which of the following is a defining characteristic that all protobionts had in
common?
A. the ability to synthesize enzymes
B. the ability to replicate RNA
C. a surrounding membrane or membrane-like structure
D. RNA genes - ✔✔C. a surrounding membrane or membrane-like structure
✔✔The first genetic material on Earth was probably ____.
A) DNA molecules whose information was transcribed to RNA and later translated in
polypeptides.
B) self-replicating RNA molecules
C) DNA produced by reverse transcriptase from abiotically produced RNA
D) oligopeptides located within protobionts - ✔✔B) self-replicating RNA molecules
✔✔Why are fossils so important in terms of evolutionary and biological study of the
planet Earth?
A) Fossils show us the forms of life that have gone extinct, but were clearly resident of
Earth at one point.
B) Fossils can be dated and thus the age (when it resided on this planet) of the
organism can be determined from the fossil.
C) In general, soft-bodied organisms only had to reside on the planet for a short period
of tie to become fossilized.
D) Both A and B.
E) Both A, B, and C. - ✔✔D) Both A and B.
✔✔Which of these observations give the most support to the endosymbiotic theory for
the origin of eukaryotic cells?
A) the similarity in size between the cytosolic ribosomes of prokaryotes and the
ribosomes within mitochondria and chloroplasts
B) the existence of structural and molecular differences between the plasma
membranes of prokaryotes and the internal membranes of mitochondria and
chloroplasts
C) the observation that some eukaryotic cells lack mitochondria
D) the size disparity between most prokaryotic cells and most eukaryotic cells - ✔✔A)
the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes
within mitochondria and chloroplasts
✔✔stanley miller's 1953 experiments supported the hypothesis that ________.
A) life on Earth arose from simple organic molecules, with energy from lightning and
volcanoes.
B) the conditions on early Earth were conducive to the origin of life.
