Bio 4B Final Exam questions correctly answered
2025 updated
1. Know the mechanisms of evolu- 1. Natural Selection: Ottspring who inherit
favorable traits will
tion. have better survival and reproductive success than
ottspring without such traits. Over time, those traits
become more com- mon in the population.
*This is the most common mechanism.
*This is the only mechanism of adaptive evolution
(results in adaptations being common in the
population).
2. Mutation: Introducing new alleles to a
population results in a change in the gene pool.
3. Genetic drift: Changes to allele frequency due
to random chance, not due to certain alleles being
more favorable than others.
* Most likely to occur in small populations.
4. Gene Flow (Migration): Changes to allele
2. Know the three ways in frequency due to individuals entering or leaving the
which natural selection population.
can alter a population.
Natural selection can alter variation in a population
in three ways:
1. Directional Selection: Occurs when individuals
with traits on one side of the mean in their
population survive better or reproduce more. Ex:
Grey mice survive better/reproduce more.
2. Stabilizing Selection: A type of natural
selection in which genetic diversity decreases as the
population stabilizes on a particular trait valve. Ex:
,Bio 4B Final Exam questions correctly answered
2025 updated
Mice stabilize on being light grey (in
between).
3. Disruptive Selection: A mode of
natural selection in which extreme values
for a trait are favored over intermediate
val- ues. Ex: Only white mice or dark grey
mice, no light grey.
,Bio 4B Final Exam questions correctly answered
2025 updated
3. Know how secondary sex Sexual selection may lead to secondary sex
char- acteristics evolve.
characteristics in animals.
Secondary sex characteristics: traits presented in males
only or females only.
*Coloration, i.e. in many bird and fish species, males
are more colorful than females.
*Anatomy, i.e. elk males have antlers whereas
females do not.
*Behavior, i.e. male tree frogs and male mockingbirds
make prolonged and complicated vocalizations to
4. Know what is the attract females.
biological species
concept. Biological species concept: Populations are of two
ditterent species if they cannot produce fertile
5. Know the different types of ottspring together.
re- productive barriers.
Reproductive barriers: Biological barriers that prevent
two individuals from successfully producing fertile
ottspring.
Prezygotic barriers: Barriers to producing a zygote.
1. Habitat isolation: Lack of opportunities to
encounter each other.
2. Temporal isolation: Breeding at ditterent times or
, Bio 4B Final Exam questions correctly answered
2025 updated
seasons.
3. Behavioral isolation: Ditterent courtship
rituals.
4. Mechanical isolation: Physical
incompatibility of reproduc- tive parts (Some
flowers can only be pollinated by hum-
mingbirds with long, curved bills while
others can only be
2025 updated
1. Know the mechanisms of evolu- 1. Natural Selection: Ottspring who inherit
favorable traits will
tion. have better survival and reproductive success than
ottspring without such traits. Over time, those traits
become more com- mon in the population.
*This is the most common mechanism.
*This is the only mechanism of adaptive evolution
(results in adaptations being common in the
population).
2. Mutation: Introducing new alleles to a
population results in a change in the gene pool.
3. Genetic drift: Changes to allele frequency due
to random chance, not due to certain alleles being
more favorable than others.
* Most likely to occur in small populations.
4. Gene Flow (Migration): Changes to allele
2. Know the three ways in frequency due to individuals entering or leaving the
which natural selection population.
can alter a population.
Natural selection can alter variation in a population
in three ways:
1. Directional Selection: Occurs when individuals
with traits on one side of the mean in their
population survive better or reproduce more. Ex:
Grey mice survive better/reproduce more.
2. Stabilizing Selection: A type of natural
selection in which genetic diversity decreases as the
population stabilizes on a particular trait valve. Ex:
,Bio 4B Final Exam questions correctly answered
2025 updated
Mice stabilize on being light grey (in
between).
3. Disruptive Selection: A mode of
natural selection in which extreme values
for a trait are favored over intermediate
val- ues. Ex: Only white mice or dark grey
mice, no light grey.
,Bio 4B Final Exam questions correctly answered
2025 updated
3. Know how secondary sex Sexual selection may lead to secondary sex
char- acteristics evolve.
characteristics in animals.
Secondary sex characteristics: traits presented in males
only or females only.
*Coloration, i.e. in many bird and fish species, males
are more colorful than females.
*Anatomy, i.e. elk males have antlers whereas
females do not.
*Behavior, i.e. male tree frogs and male mockingbirds
make prolonged and complicated vocalizations to
4. Know what is the attract females.
biological species
concept. Biological species concept: Populations are of two
ditterent species if they cannot produce fertile
5. Know the different types of ottspring together.
re- productive barriers.
Reproductive barriers: Biological barriers that prevent
two individuals from successfully producing fertile
ottspring.
Prezygotic barriers: Barriers to producing a zygote.
1. Habitat isolation: Lack of opportunities to
encounter each other.
2. Temporal isolation: Breeding at ditterent times or
, Bio 4B Final Exam questions correctly answered
2025 updated
seasons.
3. Behavioral isolation: Ditterent courtship
rituals.
4. Mechanical isolation: Physical
incompatibility of reproduc- tive parts (Some
flowers can only be pollinated by hum-
mingbirds with long, curved bills while
others can only be
