Bio250 Exam 2025 Questions with
Accurate Solutions
Most countries are expected to undergo a demographic transition at some point. Which
of the following offers the best description of a typical demographic transition?
High death rate declines before high birth rate decline. The population size increases rapidly
and levels off when birth rate once again equals death rate.
In the r- vs. K-selection classification, which of the following best describes a K-selected
species?
Individuals grow larger, live longer, reproduce later, and invest more resources into
each offspring
Recall Grime's life history classification, shown in simplified form in the figure below. In
some climates, streams are subject to frequent flash floods that scour the stream bed,
removing nearly all of the vegetation. Between floods, plants may colonize and grow in well-
lit stream channels. Which life history strategy should be most prevalent in the channels of
streams with frequent flash floods?
Ruderal (lower right corner)
The life-history strategy of coho salmon varies with latitude. Northern populations have
evolved a periodic strategy (red circle on graph), producing a lot of small eggs. Which of
the following statements best summarizes the difference in strategy between northern
and southern populations (Hint: Refer to the Winemiller and Rose classification system)
Southern populations have more of an equilibrium strategy, suggesting competition is a
more important driver of life history in the south than in the north.
Mayflies are semelparous species, reproducing only once in their lives. Nymphs (juveniles)
feed and grow in streams. Once they metamorphose into adults, they emerge from the
stream, reproduce, and then die. Females produce hundreds to thousands of eggs, and the
, adult phase is so short that adults lack mouth parts and cannot feed. What is the life-history
trade-off mayflies make by adopting this strategy?
They sacrifice adult survivorship for higher fecundity
Which of the following offers the best explanation of the Principle of Allocation, a
concept underlying nearly every trade-off represented by a life-history strategy?
Resources devoted to one function or trait cannot be devoted to another.
Why do the life-history strategies of populations and species evolve over multiple
generations?
Life-history traits are at least partially heritable, and sometimes new variants perform
better than older ones.
Deep sea vents are openings in the sea floor where hot water and nutrients spew out.
Individual vents often become plugged up, while new vents can appear in far flung parts of
the ocean. You would expect to find that species who specialize at living around these vents
are especially good at:
dispersal
Roads often decrease dispersal rates for animals and can divide patches in two. How
might these consequences of building roads affect the survival of a metapopulation?
Roads should generally decrease metapopulation survival by reducing dispersal, which
decreases recolonization of patches.
Which of the following statements best describes the difference between a realized niche
and a fundamental niche?
A realized niche describes the conditions of the environment in which a species is actually
found, while a fundamental niche describes the potential environmental conditions
tolerated by a species.
Which of the following would NOT make up a part of a bird's fundamental niche?
Accurate Solutions
Most countries are expected to undergo a demographic transition at some point. Which
of the following offers the best description of a typical demographic transition?
High death rate declines before high birth rate decline. The population size increases rapidly
and levels off when birth rate once again equals death rate.
In the r- vs. K-selection classification, which of the following best describes a K-selected
species?
Individuals grow larger, live longer, reproduce later, and invest more resources into
each offspring
Recall Grime's life history classification, shown in simplified form in the figure below. In
some climates, streams are subject to frequent flash floods that scour the stream bed,
removing nearly all of the vegetation. Between floods, plants may colonize and grow in well-
lit stream channels. Which life history strategy should be most prevalent in the channels of
streams with frequent flash floods?
Ruderal (lower right corner)
The life-history strategy of coho salmon varies with latitude. Northern populations have
evolved a periodic strategy (red circle on graph), producing a lot of small eggs. Which of
the following statements best summarizes the difference in strategy between northern
and southern populations (Hint: Refer to the Winemiller and Rose classification system)
Southern populations have more of an equilibrium strategy, suggesting competition is a
more important driver of life history in the south than in the north.
Mayflies are semelparous species, reproducing only once in their lives. Nymphs (juveniles)
feed and grow in streams. Once they metamorphose into adults, they emerge from the
stream, reproduce, and then die. Females produce hundreds to thousands of eggs, and the
, adult phase is so short that adults lack mouth parts and cannot feed. What is the life-history
trade-off mayflies make by adopting this strategy?
They sacrifice adult survivorship for higher fecundity
Which of the following offers the best explanation of the Principle of Allocation, a
concept underlying nearly every trade-off represented by a life-history strategy?
Resources devoted to one function or trait cannot be devoted to another.
Why do the life-history strategies of populations and species evolve over multiple
generations?
Life-history traits are at least partially heritable, and sometimes new variants perform
better than older ones.
Deep sea vents are openings in the sea floor where hot water and nutrients spew out.
Individual vents often become plugged up, while new vents can appear in far flung parts of
the ocean. You would expect to find that species who specialize at living around these vents
are especially good at:
dispersal
Roads often decrease dispersal rates for animals and can divide patches in two. How
might these consequences of building roads affect the survival of a metapopulation?
Roads should generally decrease metapopulation survival by reducing dispersal, which
decreases recolonization of patches.
Which of the following statements best describes the difference between a realized niche
and a fundamental niche?
A realized niche describes the conditions of the environment in which a species is actually
found, while a fundamental niche describes the potential environmental conditions
tolerated by a species.
Which of the following would NOT make up a part of a bird's fundamental niche?
