Surprise! If you are reading this check
out the BONUS Assignment!
Print out an article/current event pertaining to
ecosystem issues and or population problems!
Bring in the article with a one page handwritten
(must be legible) or typed summary of the
article. Must include the following: article copy,
summary, your opinion…Due Friday, Oct. 22!!!—
5 bonus points toward the exam!
Proceed to the next slide for Chapter 4 Exam
Chapter 4 Exam Review
Ecosystems: How they Change
What is an interbreeding, reproducing group of
individuals of a single species?
Answer: A Population
What is it called when the number of births
within a population is approximately equal to
the number of deaths?
Answer: Population Equilibrium
If natural enemies are removed, herbivore
populations will most likely ….
Answer: Increase, overgraze, decline due to
Predict what will happen if there is an increase
in the population of an herbivore.
Answer: It will be followed by an increase in
populations of its natural enemies (think Isle
Describe how a population achieves a stable
Answer: Death rate is the same as the birth rate
What is the term for the number of offspring
that can be produced in a population under
Answer: biotic potential
What is a lethal mutation?
Answer: Changes in the genetic code that cause
What does “survival of the fittest” mean?
Answer: organisms that can best cope with
existing environmental conditions and live to
What is recruitment mean?
Answer: The percentage of offspring that reach
maturity and reproduce
What is a gene pool?
Answer: all of the variations (alleles) of all genes
present in a population of a species
What is the genetic material in all organisms?
During sexual mating, the individual offspring
will receive __________.
Answer: One set of genes from each parent
In nature, how are herbivore population
regulated and kept balanced?
Answer: Natural enemies (predators) keep
herbivores from overgrazing
Compared to rates of change which occur in
nature, how can you describe human-induced
Answer: Extremely rapid
What is the term that refers to the ability of an
individual to attain breeding age?
What is the critical number of a species referring
Answer: The minimum number of individuals
needed to sustain a breeding population
What are some examples of selective pressures?
Answer: predator-prey relationships,
competition and herbivory
True or False?
All individuals of a species have identical DNA.
What phrase is often used to describe Darwin’s
views on natural selection?
Answer: “Survival of the Fittest”
Survival of the fittest does not refer just to an
organism’s ability to survive but also its ability
How does territoriality limit populations?
Answer: Individuals or groups that cannot
acquire and defend a territory are prevented
True or False?
Mutations always benefit the survival of the
What is replacement level?
Answer: Reproductive rates that just maintain
the size of the population
If conditions change such that they are beyond
the limit of tolerance for most but not all
members of the population, what can be said
about the survivors?
Answer: The survivors will give rise to a new
population which is better adapted to the new
What is a selective pressure?
Answer: a biotic or abiotic factor that affects
the reproductive ability of a species
What is the segment of DNA that provides the
genetic instructions for making a single
Answer: A Gene
When would an herbivore population be likely
to experience the J-curve population change?
Answer: When the environment would be
lacking herbivore predators
What can one expect to happen to a species
after many generations of feeding at night?
Answer: Over the generations, the population
will become increasingly well adapted to
feeding at night
In ecology, what does succession refer to?
Answer: change in a community over time; one
species or group of species gradually being
replaced by another
The combination of abiotic and biotic factors
that may limit population growth is called
Answer: Environmental Resistance
What is carrying capacity?
Answer: The maximum population density that
a habitat can support without experiencing
Give an example of a species that is unlikely to
have a high biotic potential.
Answer: A species that has an intense
protection of its young (high parental care)
Describe what is happening within a population
Answer: according to the S-curve.
then levels off
below are near
What is likely to happen if one or more
conditions change so rapidly that they go
beyond the species’ limit of tolerance?
Answer: the species will become extinct
What is it called when one species diverges into
two or more species?
As a result of adaptation, a(n)__________ is
more fit and successful.
A) Individual organism B) gene C)population
If and when environmental factors change, what
options does a species have for survival?
Answer: Migrate, Adapt, or Die
How can fires be beneficial to some
Answer: Fires release nutrients and
help restore energy balance in the
Explain what this graph represents.
Answer: There is a population explosion (most likely due to
human interference) causing the population to exhaust all of
its resources thus beginning to die off.
What is a climax ecosystem?
Answer: A stable ecosystem in which the
populations of all species are in balance and
without interruption or change can exist
Give examples of events that can alter the
carrying capacity of an area.
Answer: fire, introduction of a predator,
invasive species introduction, supplemental
feedings for species
Give a present day example of organisms
undergoing change by natural selection?
Answer: Insect populations becoming resistant
to insecticides, bacteria becoming resistant to
antibiotics, weeds becoming resistant to
What factors contribute to the evolution of a
Answer: mutations, physical isolation, exposure
of isolated groups to different selective
How have humans caused ecological upsets?
Answer: Elimination of predators, introduction
of new species, creating monocultures
(limiting diversity), habitat destruction,
Give 3 examples of field signs.
Answer: tracks, prints, hair or fur, nests, poo,
seedlings, road kill, shells, disturbed material
**Invasive Species examples
**Exam Day is MONDAY, OCT. 25!