TAMU BIOLOGY 112 EXAMS SCRIPT 2025/2026 QUESTIONS
WITH ANSWERS RATED A+
✔✔What does genetic drift lead to? - ✔✔Leads to loss of an allele from the gene pool
✔✔Genetic Drift is caused by - ✔✔Random catastrophic events
✔✔Founder Effect - ✔✔Few individuals become isolated from a population and their
gene pools differ
✔✔Bottleneck Effect - ✔✔Sudden change in environment may reduce size of
population
✔✔What is the negative effect of the founder population? - ✔✔High frequency of
inherited disorders among isolated human populations
✔✔Consequences of Bottleneck Effect? - ✔✔Causes low genetic variation
-Random alleles may be overrepresented or absent
✔✔What type of populations is genetic drift significant in? - ✔✔Small Populations
✔✔Directional Selection - ✔✔-Favor one extreme
✔✔Disruptive Selection - ✔✔-Extremes are favored over intermediate
✔✔Stabilizing Selection - ✔✔-Favors intermediate
-Reduces variation
✔✔Sexual Selection - ✔✔Individuals with certain inherited characteristics are more
likely than another individual of the same sex to obtain mates
✔✔What can sexual selection lead to? - ✔✔Sexual dimorphism
✔✔Sexual Dimorphism - ✔✔A difference in secondary sexual characteristics between
males and females of the same species
✔✔Heterozygote advantage - ✔✔Individuals who are heterozygous at a locus have
greater fitness than do both kinds of homozygotes
✔✔Heterozygote advantage - ✔✔2 or more alleles at a locus
-Genotype not phenotype
✔✔Key observation of the unifying theory of life? - ✔✔Many characteristics are shared
by all living things
,✔✔Lyell's principle of uniformitarianism __________ - ✔✔strongly influenced Darwin's
view of how living organisms could change over time
✔✔Darwin... - ✔✔He proposed natural selection as the mechanism of evolution.
✔✔Similarities between developmental stages of chickens and humans is an argument
for... - ✔✔common ancestry
✔✔If a population is in HWE, then the proportion of the heterozgyotes in the population
can be determined by solving for the value of - ✔✔2pq
✔✔With the soapberry bugs that evolved shorter beaks as they began feeding on
introduced raintree pods instead of their native balloon vine pods. If this is truly an
example of natural selection, what MUST be true? - ✔✔The length of the beak is a
heritable characteristic
✔✔As one looks further in the past, transitional fossils in the evolution of whales...
A. Look less and less like whales
B. Have less flipper-like forelimbs
C. Have limb bones more like land-dwelling deer
D. Have more robust hindlimbs
E. All of the Above - ✔✔E
✔✔You are a botanist and find a new species C with 2n=24 chromosome number. If this
is an allopolyploid species derived from species A and B, then - ✔✔Species A is 2n=16
Species B is 2n=8
✔✔Evidence supports the conclusion that new species have been formed from pre-
existing species. The most common process for this requires... - ✔✔A geographic
barrier
✔✔Homozygous recessive animals have very short crystal fur and those with the
dominant allele have long crystal fur. The recessive allele t is found in the population at
a rate of 36 out of 100 alleles. What is the allele frequency of the dominant allele T? -
✔✔0.64
✔✔What describes mechanical isolation prezygotic barrier? - ✔✔Two snails have shells
that spiral in different directions
✔✔True or False: Darwin's book, On the Origin of Species, was not published until
several years after his death - ✔✔False
, ✔✔True or False: Darwin's geological observations convinced him that
uniformitarianism was a correct concept - ✔✔True
✔✔Disruptive Selection - ✔✔
✔✔Stabilizing Selection - ✔✔
✔✔Directional Selection - ✔✔
✔✔The idea of evolution of life over time by means of natural selection was developed
independently by - ✔✔Wallace
✔✔Which process is the LEAST random?
A. Bottleneck effect
B. Point mutation
C. Fertilization
D. Genetic Drift
E. Natural Selection - ✔✔E. Natural Selection
✔✔The production of sterile mules by interbreeding between female horses and male
donkeys is an example of - ✔✔Reduced hybrid fertility
✔✔If biological species are defined in terms of reproductive compatibility, the formation
of a new species hinges on - ✔✔reproductive isolation
✔✔30 species of shrimp live in the coast of Panama. Panama formed as a land bridge
between the America's a long ass time ago. What was the evidence that this present
species diversity is the result of allopatric speciation - ✔✔Genetic analysis concluded
that the closest relative each of fifteen Atlantic species is one of fifteen species from the
Pacific
✔✔Order of events in allopatric speciation - ✔✔Genetic isolation, genetic drift,
divergence
✔✔Frequency dependent selection - ✔✔an evolutionary process by which the fitness of
a phenotype depends on its frequency relative to other phenotypes in a given
population. In positive frequency-dependent selection, the fitness of a phenotype
increases as it becomes more common.
✔✔If Darwin sorted his finches by wingspan and beak size, he would be defining -
✔✔morphological species
WITH ANSWERS RATED A+
✔✔What does genetic drift lead to? - ✔✔Leads to loss of an allele from the gene pool
✔✔Genetic Drift is caused by - ✔✔Random catastrophic events
✔✔Founder Effect - ✔✔Few individuals become isolated from a population and their
gene pools differ
✔✔Bottleneck Effect - ✔✔Sudden change in environment may reduce size of
population
✔✔What is the negative effect of the founder population? - ✔✔High frequency of
inherited disorders among isolated human populations
✔✔Consequences of Bottleneck Effect? - ✔✔Causes low genetic variation
-Random alleles may be overrepresented or absent
✔✔What type of populations is genetic drift significant in? - ✔✔Small Populations
✔✔Directional Selection - ✔✔-Favor one extreme
✔✔Disruptive Selection - ✔✔-Extremes are favored over intermediate
✔✔Stabilizing Selection - ✔✔-Favors intermediate
-Reduces variation
✔✔Sexual Selection - ✔✔Individuals with certain inherited characteristics are more
likely than another individual of the same sex to obtain mates
✔✔What can sexual selection lead to? - ✔✔Sexual dimorphism
✔✔Sexual Dimorphism - ✔✔A difference in secondary sexual characteristics between
males and females of the same species
✔✔Heterozygote advantage - ✔✔Individuals who are heterozygous at a locus have
greater fitness than do both kinds of homozygotes
✔✔Heterozygote advantage - ✔✔2 or more alleles at a locus
-Genotype not phenotype
✔✔Key observation of the unifying theory of life? - ✔✔Many characteristics are shared
by all living things
,✔✔Lyell's principle of uniformitarianism __________ - ✔✔strongly influenced Darwin's
view of how living organisms could change over time
✔✔Darwin... - ✔✔He proposed natural selection as the mechanism of evolution.
✔✔Similarities between developmental stages of chickens and humans is an argument
for... - ✔✔common ancestry
✔✔If a population is in HWE, then the proportion of the heterozgyotes in the population
can be determined by solving for the value of - ✔✔2pq
✔✔With the soapberry bugs that evolved shorter beaks as they began feeding on
introduced raintree pods instead of their native balloon vine pods. If this is truly an
example of natural selection, what MUST be true? - ✔✔The length of the beak is a
heritable characteristic
✔✔As one looks further in the past, transitional fossils in the evolution of whales...
A. Look less and less like whales
B. Have less flipper-like forelimbs
C. Have limb bones more like land-dwelling deer
D. Have more robust hindlimbs
E. All of the Above - ✔✔E
✔✔You are a botanist and find a new species C with 2n=24 chromosome number. If this
is an allopolyploid species derived from species A and B, then - ✔✔Species A is 2n=16
Species B is 2n=8
✔✔Evidence supports the conclusion that new species have been formed from pre-
existing species. The most common process for this requires... - ✔✔A geographic
barrier
✔✔Homozygous recessive animals have very short crystal fur and those with the
dominant allele have long crystal fur. The recessive allele t is found in the population at
a rate of 36 out of 100 alleles. What is the allele frequency of the dominant allele T? -
✔✔0.64
✔✔What describes mechanical isolation prezygotic barrier? - ✔✔Two snails have shells
that spiral in different directions
✔✔True or False: Darwin's book, On the Origin of Species, was not published until
several years after his death - ✔✔False
, ✔✔True or False: Darwin's geological observations convinced him that
uniformitarianism was a correct concept - ✔✔True
✔✔Disruptive Selection - ✔✔
✔✔Stabilizing Selection - ✔✔
✔✔Directional Selection - ✔✔
✔✔The idea of evolution of life over time by means of natural selection was developed
independently by - ✔✔Wallace
✔✔Which process is the LEAST random?
A. Bottleneck effect
B. Point mutation
C. Fertilization
D. Genetic Drift
E. Natural Selection - ✔✔E. Natural Selection
✔✔The production of sterile mules by interbreeding between female horses and male
donkeys is an example of - ✔✔Reduced hybrid fertility
✔✔If biological species are defined in terms of reproductive compatibility, the formation
of a new species hinges on - ✔✔reproductive isolation
✔✔30 species of shrimp live in the coast of Panama. Panama formed as a land bridge
between the America's a long ass time ago. What was the evidence that this present
species diversity is the result of allopatric speciation - ✔✔Genetic analysis concluded
that the closest relative each of fifteen Atlantic species is one of fifteen species from the
Pacific
✔✔Order of events in allopatric speciation - ✔✔Genetic isolation, genetic drift,
divergence
✔✔Frequency dependent selection - ✔✔an evolutionary process by which the fitness of
a phenotype depends on its frequency relative to other phenotypes in a given
population. In positive frequency-dependent selection, the fitness of a phenotype
increases as it becomes more common.
✔✔If Darwin sorted his finches by wingspan and beak size, he would be defining -
✔✔morphological species
