Chapter 34

Ecology is best defined as the study of
organisms as they interact with other organisms and with their physical surroundings.
An ecosystem contains
both the living organisms and the abiotic components of the environment.
The relatively thin layer on the earth’s surface where life is possible is known as the
biosphere
The study of the interrelationships of plants and animals with each other and with their environment is known as
ecology
All the members of the same species that inhabit a particular area are termed a(n)
population
A number of populations of different species interacting with one another in a natural environment, such as a rotten log, is called
a community
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Consider that a species of salmon lays 20,000 eggs per pair when it spawns and dies. At the end of five years, an average of one pair of mature salmon from this group of hatched eggs returns again to spawn in the parent stream (19,998 have died). What is the per capita rate of increase?
zero, because there is exact replacement of the previous generation
The maximum per capita rate of increase for a population that can occur under ideal conditions is the
biotic potential.
When the number of births exceeds the number of deaths, this results in
population growth.
Which of the following does not impact an organism’s biotic potential?
the rate of immigration into an area
Which of the following is NOT a form of environmental resistance?
number of offspring produced per litter
A scientist observes a population of grasshoppers in a farmer’s field several times over the summer. She notices that after each application of an insecticide the grasshopper population increases to its pre-pesticide levels very rapidly and that the population never goes near zero at any time. The scientist’s results indicate the grasshopper population is probably
in the exponential growth phase.
Biotic potential depends on all of the following EXCEPT
how many different mates each individual has.
When growth proceeds at a rate similar to 2 → 4 → 8 → 16 → 32 → 64…etc., it is called
exponential growth.
A population with rapidly expanding exponential growth would be best represented by a graph with a(n) ______-shaped curve.
J
The human growth curve is best described as being
J-shaped
The carrying capacity of the environment for a species is determined by
the limited productivity of the environment and the environmental resistance to the biotic potential of the organism.
Population size is believed to level off at the _______ of an environment.
carrying capacity
connect picture
Which of the following describes a type I survivorship curve (drawn by plotting the number of individuals in a given population alive at the beginning of each age interval)?
Most individuals die of old age.
Which of the following describes a type II survivorship curve (drawn by plotting the number of individuals in a given population alive at the beginning of each age interval)?
Individuals die at a constant rate throughout time.
Which of the following describes a type III survivorship curve (drawn by plotting the number of individuals in a given population alive at the beginning of each age interval)?
Many individuals die early in life.
Consider the life of the praying mantis. The large predatory female lays several hundred eggs in a foam mass in the fall. The young are most vulnerable when they emerge in the spring, but the few that survive spread out over the countryside and, if they find a mate, lay eggs the following fall. Which type of survivorship curve does this represent?
type III
The demographic transition, where population growth slows in developed countries, may be attributed at least in part to
the rise of medicine.
Which of the following is NOT true?
As the human population increases in size, less energy but more material will be consumed.
Age structure diagrams with a broad base suggest that
the population will continue to grow for some time.
Which of the following statements accurately describes the less developed countries?
high birthrate, large pre-reproductive portion of the population
Replacement reproduction occurs when
each couple has an average of two children, but may still allow for population growth.
A population age structure in which the birthrate is high and the population is mainly young would be best represented by a graph with a(n)
pyramid shape.
Farmers sprayed leechi trees to suppress populations of scale insects. This also killed the populations of a predatory lacewing that controlled the numbers of scales. Soon the spraying did no good, and the damage to the leechi from the scales was greater than before spraying had occurred. Few predatory lacewings existed in the trees now because
the scale insect was an opportunistic species and the high number of young included a resistant strain; the predator was an equilibrium species and will take longer to produce a resistant variety.
In nature animals tend to be either an opportunistic or equilibrium species or somewhere along an intermediate point between the two. Why aren’t there animals in nature that are both big, fierce and highly reproductive so they leave many offspring?
You can “spend” your energy to be a large equilibrium species, to produce many offspring as an opportunistic species, or to be somewhere in between, but you can’t spend the energy to be both large and highly reproductive.
The conditions under which an organism survives and exists in the community is called its
ecological niche
There are several species of grain beetles that can live on dry meal obtaining water mostly as metabolic water. Many of these beetle species are grain pests that do considerable damage to stored grain. You set up a dozen jars of dry meal and introduce fifty individuals of each species to each jar, being careful to have half of each species from each sex. The food supply is sufficient to last for a year and the size is adequate so that wastes do not become toxic. Most likely, examination of the jars in six months will find
only one species per jar, similar to the classic experiment with paramecia.
There are two organisms with overlapping ranges and filling a similar niche. We find that where their niches overlap, there is twice the competition for resources. This leads to
competitive exclusion
Which term describes the concept that no two species can have the same “job” in the community at the same time?
competitive exclusion
Interaction between two species as both attempt to use the same environmental resources is
competition
In large natural ecosystems, competition between two species over time will usually result in
each species occupying a slightly different niche.
Similar species occupying slightly different niches in the same community is shown by
competition between two species of barnacles in Scotland resulting in one living in the intertidal zone and the other living below this species.
Interaction between two species in which one feeds on the other is
predation
The harmless orange-and-black viceroy butterfly closely resembling the toxic orange-and-black monarch butterfly is an example of
Batesian mimicry
Which statement is NOT true about parasitism?
Parasites are always severe and usually kill a host.
Parasites are found
in all kingdoms and sometimes one parasite uses more than one host to disperse.
Which is NOT a parasitic relationship?
Unsightly dandelions sprout in a yard and compete with the fescue grass for sunlight.
A form of symbiosis in which one participant benefits and the other apparently is not benefited nor harmed is
commesalism
An example of commensalism is
clown fishes in sea anemones.
The theory that plants cannot grow on a particular area until the soil has been developed enough by an earlier community is the
facilitation model
In a population of 10000 organisms over a one year period there are 750 births and 130 deaths. Calculate the growth rate for that year.
0.062
In a pine forest few other species of plants grow under the pines because the needles of pine trees are acidic and make the soil more acidic. This is an example of
The inhibition model
One model proposed for succession predicts that different types of plants can all colonize an area at the same time and it is chance alone that determines which one arrives first and begins the process of succession. This model is called
The tolerance model
The climax pattern model states that the same area will always lead to a specific type of community if it is given a sufficient amount of time. Which of the following statements is true of this model?
In recent time this has been modified to recognize that while the area may return to the same biome it may not have exactly the same species diversity.