BIOL 313 Midterm 1 Exam Questions with Correct Answers Latest Update 2026/2027
Evolution - Answers Change over time in the proportions of individual organisms that differ
genetically in one or more traits
Micro evolution - Answers Change over time in the proportions of individuals that alters the
characteristics of a species (WITHIN A SPECIES)
Macro evolution - Answers Change over time in the proportion of species that determines the
diversity of different taxonomic groups (new species)
4 aspects of Natural Selection - Answers A) more offspring are produced each generation than
can be supported by the environment
B) there is variation in physical, physiological and behavioural traits among individuals in the
population, some are heritable others are mutations
C) some traits are more advantageous allowing some individuals to have better fitness *NS is
nonrandom
D) traits that result in increased fitness will become more common within a population over
subsequent generations
Stabilizing selection - Answers The dominant/average phenotype has the greatest fitness,
variation in the population will decrease
Directional selection - Answers Selection gradient will choose one of the extremes, trait size will
move in that direction
Disruptive selection - Answers When BOTH extremes have greater fitness , bimodal distribution
will develop, overall variation increases *speciation can occur
Frequency dependent selection - Answers Fitness of an individual depends on the relative
frequency of other phenotypes
Evolutionary stable state - Answers When all phenotypes have the same fitness
Biological Species Concept - Answers Species are groups of actually or potentially interbreeding
natural populations that are reproductively isolated from other groups
Cladogenesis - Answers The result of speculation when there is branching out of an
evolutionary lineage
Allopatric speciation - Answers Geographic barriers or distance prevents gene flow and
populations can evolve independently
Parapatric speciation - Answers Occurs when a population expands into a new habitat within
, the preexisting range of the parent species
Sympatric speciation - Answers Development of reproductive isolation between two segments
of a single population that are in continuous contact
-usually causes disruptive selection
Physiological ecology - Answers The study of biophysical, biochemical, and physiological
processes used by plants and animals to cope with factors of their physical environment, or
employed during ecological interactions with other organisms
Ex. Kangaroos have adapted to hot weather by having blood vessels close to the outer skin so
they can lick their arms and evaporation cools their blood
2 abiotic factors of physiological ecology - Answers 1) resource- abiotic factor consumed by an
individual and therefore less available to others
2) condition- abiotic factors that vary in time and space which organisms respond to differently
Poikilotherms - Answers Body temperature fluctuates with ambient temperature of the
environment
Homeotherms - Answers Maintain relatively constant body temperature despite changes in
ambient temperature
A)ectotherms-regulate body temp. By selecting appropriate thermal environments
B) endotherms- regulate body temperature by using internal metabolic processes
Heterotherms - Answers Are homeothermic sometimes and poikilothermic other times
Thermal performance curve - Answers Performance of an organism based on ambient
temperature
Endothermic thermal performance curve - Answers Performance optima (thermal neutral zone)
is where no energy is expended to maintain optima
Ectothermic thermal performance curve - Answers Use behaviour to find the optimal
environment that allows for optimal performance
Lethal temperature (LT50) - Answers Upper and lower temperature at which 50% of organisms
die
Critical temperature (CT MAX OR MIN) - Answers Temperature is increased or decreased and
the point at which death is imminent
3 implications of thermal performance curves - Answers 1) distribution limits-geographically,
temporally
Evolution - Answers Change over time in the proportions of individual organisms that differ
genetically in one or more traits
Micro evolution - Answers Change over time in the proportions of individuals that alters the
characteristics of a species (WITHIN A SPECIES)
Macro evolution - Answers Change over time in the proportion of species that determines the
diversity of different taxonomic groups (new species)
4 aspects of Natural Selection - Answers A) more offspring are produced each generation than
can be supported by the environment
B) there is variation in physical, physiological and behavioural traits among individuals in the
population, some are heritable others are mutations
C) some traits are more advantageous allowing some individuals to have better fitness *NS is
nonrandom
D) traits that result in increased fitness will become more common within a population over
subsequent generations
Stabilizing selection - Answers The dominant/average phenotype has the greatest fitness,
variation in the population will decrease
Directional selection - Answers Selection gradient will choose one of the extremes, trait size will
move in that direction
Disruptive selection - Answers When BOTH extremes have greater fitness , bimodal distribution
will develop, overall variation increases *speciation can occur
Frequency dependent selection - Answers Fitness of an individual depends on the relative
frequency of other phenotypes
Evolutionary stable state - Answers When all phenotypes have the same fitness
Biological Species Concept - Answers Species are groups of actually or potentially interbreeding
natural populations that are reproductively isolated from other groups
Cladogenesis - Answers The result of speculation when there is branching out of an
evolutionary lineage
Allopatric speciation - Answers Geographic barriers or distance prevents gene flow and
populations can evolve independently
Parapatric speciation - Answers Occurs when a population expands into a new habitat within
, the preexisting range of the parent species
Sympatric speciation - Answers Development of reproductive isolation between two segments
of a single population that are in continuous contact
-usually causes disruptive selection
Physiological ecology - Answers The study of biophysical, biochemical, and physiological
processes used by plants and animals to cope with factors of their physical environment, or
employed during ecological interactions with other organisms
Ex. Kangaroos have adapted to hot weather by having blood vessels close to the outer skin so
they can lick their arms and evaporation cools their blood
2 abiotic factors of physiological ecology - Answers 1) resource- abiotic factor consumed by an
individual and therefore less available to others
2) condition- abiotic factors that vary in time and space which organisms respond to differently
Poikilotherms - Answers Body temperature fluctuates with ambient temperature of the
environment
Homeotherms - Answers Maintain relatively constant body temperature despite changes in
ambient temperature
A)ectotherms-regulate body temp. By selecting appropriate thermal environments
B) endotherms- regulate body temperature by using internal metabolic processes
Heterotherms - Answers Are homeothermic sometimes and poikilothermic other times
Thermal performance curve - Answers Performance of an organism based on ambient
temperature
Endothermic thermal performance curve - Answers Performance optima (thermal neutral zone)
is where no energy is expended to maintain optima
Ectothermic thermal performance curve - Answers Use behaviour to find the optimal
environment that allows for optimal performance
Lethal temperature (LT50) - Answers Upper and lower temperature at which 50% of organisms
die
Critical temperature (CT MAX OR MIN) - Answers Temperature is increased or decreased and
the point at which death is imminent
3 implications of thermal performance curves - Answers 1) distribution limits-geographically,
temporally
