ashworth college SC260 online exam 6 latest 2014 jan.

Part 1 of 1 – 100.0
Points

Question 1 of 20
5.0 Points
Joseph Connell’s “intermediate disturbance
hypothesis” proposes that:
A. species diversity
is highest at intermediate frequencies of disturbance.
B. species diversity
is lowest at intermediate frequencies of disturbance.
C. population growth
rates are highest at intermediate frequencies of disturbance.
D. competitive
exclusion is fastest at intermediate levels of disturbance.

Question 2 of 20
5.0 Points
A “community” is defined as:
A. a group of
organisms that all make their living in a similar way.
B. a group of
individuals of a single species inhabiting a defined area.
C. the portion of a
defined area that supports life.
D. an association of
interacting species inhabiting a defined area.

Question 3 of 20
5.0 Points
In most ecological communities:
A. most species are
extremely rare.
B. few species are
very abundant.
C. most species are
moderately abundant.
D. both few species
are very abundant, and most species are moderately abundant.

Question 4 of 20
5.0 Points
Robert MacArthur’s study of forest warblers suggested that:
A. fewer warbler
species can survive in more complex habitats.
B. warbler species
diversity increases with habitat complexity.
C. warbler species
diversity decreases with habitat complexity.
D. most warblers
have rather similar foraging niches.

Question 5 of 20
5.0 Points
Niches of single-celled algae, such as diatoms, seem most
often to be distinguished by their requirements for:
A. different
combinations of inorganic nutrients.
B. different light
environments.
C. different water-flow
environments.
D. different water
temperatures.

Question 6 of 20
5.0 Points
In the Amazon forest, slight changes in soil properties tend
to be correlated with:
A. similar, slight
differences in plant communities.
B. no detectable
differences in plant communities.
C. dramatic
differences in plant communities.
D. dramatic
differences in plant communities only if the soil property in question is
moisture.

Question 7 of 20
5.0 Points
In Robert Paine’s studies of the Washington intertidal
community, which organism proved to be a keystone species?
A. The whelk Thais
B. Acorn barnacles
C. Chitons
D. The starfish
Pisaster

Question 8 of 20
5.0 Points
In the Washington intertidal community studied by Robert
Paine, the most important limiting resource is:
A. space.
B. light.
C. plankton.
D. nitrogen.

Question 9 of 20
5.0 Points
We can infer a statistically significant difference between two
population means when:
A. our estimates of
the two means are different.
B. the variances of
the two means do not overlap.
C. the standard
deviations of the two means do not overlap.
D. the 95%
confidence intervals for the two means do not overlap.

Question 10 of 20
5.0 Points
Weaver ants provide effective protection of citrus trees
because they:
A. remove harmful
soft-scale insects (mealybugs).
B. remove all
plant-feeding insects.
C. cultivate
soft-scale insects, but do not allow them to feed on the trees.
D. cultivate
soft-scale insects, but still allow them to be attacked by parasitoids and
predators.

Question 11 of 20
5.0 Points
The Nile perch population explosion has been accompanied by:
A. a decrease in the
dissolved oxygen in the shallowest portions of Lake Victoria.
B. a decrease in the
dissolved oxygen in the deepest portions of Lake Victoria.
C. an increase in
the dissolved oxygen in the deepest portions of Lake Victoria.
D. an increase in
the dissolved oxygen in the shallowest portions of Lake Victoria.

Question 12 of 20
5.0 Points
Based on studies by Jane Lubchenko, what influence does the
population density of the herbivorous intertidal snail, Littorina littorea, have
on the number of algal species?
A. As snail density
increases from low to medium, the number of algal species increases.
B. As snail density
increases from medium to high, the number of algal species increases.
C. As snail density
increases from medium to high, the number of algal species decreases.
D. Both as snail
density increases from low to medium the number of algal species increases and
as snail density increases from medium to high, the number of algal species
decreases.

Question 13 of 20
5.0 Points
Teja Tscharntke simplified the food web associated with the
wetland reed Phragmites australis by dividing the species into the following
major trophic levels?
A. Plant, herbivore,
piscivore, and granivore
B. Herbivore,
carnivore, detritivore, and consumer
C. Herbivore,
parasite, carnivore, and detritivore
D. Plant, herbivore,
parasite, and carnivore

Question 14 of 20
5.0 Points
Net primary productivity is the primary productivity of an
ecosystem, after subtracting energy lost in:
A. dead plant
tissues.
B. inedible plant
tissues.
C. respiration by
primary producers.
D. respiration by
primary consumers.

Question 15 of 20
5.0 Points
“Actual evapotranspiration” for an ecosystem
refers to the amount of water that:
A. is taken up from
soils by plant roots.
B. evaporates from
soils.
C. is transpired by
plants.
D. evaporates from
soils plus the amount transpired by plants.

Question 16 of 20
5.0 Points
Leibig’s “Law of the Minimum” stated that:
A. the lowest
primary productivity occurs in the coldest ecosystems.
B. primary
productivity is typically controlled entirely by climate.
C. primary
productivity is typically controlled by both climate and soil nutrients.
D. a single soil
nutrient typically limits primary productivity.

Question 17 of 20
5.0 Points
Experimental fertilizations in the Baltic Sea suggest that
primary productivity there is normally limited by:
A. phosphorus.
B. nitrogen.
C. iron.
D. potassium.

Question 18 of 20
5.0 Points
The “trophic cascade hypothesis” emphasizes the
role of:
A. nutrients in
controlling primary productivity.
B. nutrients in
controlling primary consumption.
C. grazing by
herbivores in controlling primary productivity.
D. grazing by
herbivores in controlling ecosystem nutrient levels.

Question 19 of 20
5.0 Points
In Hubbard Brook Experimental Forest, the largest
“standing stock” of energy is represented by biomass of:
A. living plant
tissues.
B. dead plant
tissues.
C. invertebrate
herbivores.
D. vertebrate
herbivores.

Question 20 of 20
5.0 Points
An increase about 1,000 years ago in 13C content of human
collagen from archeological sites in eastern North America probably records:
A. replacement of
vegetables and grains in the diet by meat.
B. replacement of
corn by beans and squash in the diet.
C. increasing
consumption of corn.
D. increasing levels
of 13C in soils.