front 1 - Based on the data, which of the following is the most likely
effect of a period of increased volcanic activity that significantly
decreases the amount of sunlight reaching a particular ecosystem for
several years?
- A) There will be a decrease in the population sizes of most
species and a decrease in the number of trophic levels.
- B)
The population sizes of plant species will stay the same, but the
average biomass of individual plants will increase.
- C)
There will be an increase in the population sizes of omnivores
because they can eat other animals instead of the plants.
- D) The biodiversity of the ecosystem will increase as new niches
arise and become occupied by new species.
| back 1 - A) There will be a decrease in the population sizes of most
species and a decrease in the number of trophic levels.
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front 2 - Which of the following is an appropriate null hypothesis for
the student's experiment?
- A) The absence of light negatively affects the mass of the
grass.
- B) An increase in light promotes grass growth.
- C) A change in light intensity changes the rate of grass
growth.
- D) The presence of light has no effect on the mass of
the grass.
| back 2 - D) The presence of light has no effect on the mass of the
grass.
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front 3 - Based on the data, which of the following is the best
approximation of the rate of growth per week in section IIII from
day 14 to day 21 ?
- A) 3.2g/week
- B) 4.5g/week
- C) 5.1g/week
- D) 9.6g/week
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front 4 - Which of the following best explains the observed difference in
mass between the grass in section I after 14 days and the grass in
section III after 21 days?
- A) The grass in section III required more energy for metabolic
processes than the grass in section I.
- B) The grass in
section III performed more photosynthesis than the grass in section
I.
- C) Only the grass in section III used energy from the seed
for growth and development.
- D) Mass lost by cell
respiration in section III was not replaced by photosynthesis.
| back 4 - D) Mass lost by cell respiration in section III was not
replaced by photosynthesis.
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front 5 - Climate change could affect the ecosystem of the Elkhorn Slough
in many ways. From the information provided, which of the following
predictions about the direct, local effects of climate change is
most likely?
- A) Ocean warming will favor population growth of nonnative
species as their habitats shift northward.
- B) Ocean warming
will decrease eelgrass habitat area as a result of increased
herbivory by nonnative species.
- C) Harmful algal blooms
will decrease otter populations as a result of increased mortality
of otter prey species.
| back 5 - A) Ocean warming will favor population growth of nonnative
species as their habitats shift northward.
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front 6 - As otters were removed during the hunting years, there was a
large decrease in the catches of fish species from the eelgrass
habitats. Which of the following best explains why this decrease
happened?
- A) Otters are a keystone species, so their disappearance from
the area affected the population size of one other species.
- B) Otters are a keystone species, so their disappearance from
the area resulted in the collapse of an entire community.
- C) Otters have mutualistic relationships with many other
species, so their disappearance from the area affected the
population size of another species.
- D) Otters have
mutualistic relationships with many other species, so their
disappearance from the area resulted in the collapse of an entire
ecosystem.
| back 6 - B) Otters are a keystone species, so their disappearance from
the area resulted in the collapse of an entire community.
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front 7 - Based on the information provided in the passage, which of the
following best describes the effect of harmful algal blooms on otter
populations?
- A) They are a density-dependent factor that increases otter
mortality in larger populations.
- B) They are a
density-dependent factor that reduces otter numbers at lower
population sizes.
- C) They are a density-independent factor
that negatively affects the otter population regardless of its
size.
- D) They are a density-independent factor that increases
otter mortality in only larger populations.
| back 7 - C) They are a density-independent factor that negatively
affects the otter population regardless of its size.
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front 8 - Based on the information, an increase in the sea slug
population would most likely be directly related to which of the
following?
- A) An increase in the eelgrass population
- B) The
introduction of nonnative invertebrates
- C) A decrease in
algae availability
- D) A decrease in the crab
population
| back 8 - D) A decrease in the crab population
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front 9 - Which of the following best describes what happened to the
otter population between 1750 and 1850 ?
A)The population decreased in size as a result of a loss of genetic diversity.
B)The population decreased in size as a result of habitat loss.
C)The population lost genetic diversity as a result of a bottleneck effect.
D)The population lost genetic diversity as a result of the founder effect. | back 9 C)The population lost genetic diversity as a result of a bottleneck effect. |
front 10 - Scientists studying a wild population of mantled howler monkeys
found the average birth rate to be 0.22 and the average death rate
to be 0.12. At the start of the study, the population consisted of
13
monkeys.
Assuming no immigration or emigration, which of the following best
describes the change in population size that will occur over the next year
- The population will increase because more monkeys are being
born each year than are dying.
| back 10 - The population will increase because more monkeys are being
born each year than are dying.
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front 11 - In the early 1970s, researchers hypothesized that carbon was
the limiting nutrient in many aquatic ecosystems. To test this
hypothesis, the researchers divided a small lake in two roughly
equal halves with an impermeable curtain that was fastened and
sealed to the bedrock of the lake. Beginning in 1971 the researchers
treated one side of the lake with sucrose and the other side with
both sucrose and phosphate. From 1971 to 1983 the researchers
monitored the phytoplankton biomass in both parts of the lake. The
results are shown in Figure 1.
Which of the following claims is best supported by the data?
- Phosphate was a limiting factor for phytoplankton in the
lake.
| back 11 - Phosphate was a limiting factor for phytoplankton in the
lake.
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front 12 - Wolves, once native to Yellowstone National Park, were hunted
to the point of complete extinction in the park. As a result, the
elk population in the park flourished, putting extra demands on the
carrying capacity of the park. Many other species, such as certain
trees and beavers, were negatively affected by the increase in
elk.
Years later, wolves were reintroduced into the park. While the elk
population decreased after the wolves returned, the beaver and
songbird populations began to increase as did the populations of
various plant species.
Which of the following best explains how wolves are a keystone
species in this ecosystem?
- Wolves help balance the population sizes of other species,
allowing more species to thrive in the wolves' presence than in
their absence.
| back 12 - Wolves help balance the population sizes of other species,
allowing more species to thrive in the wolves' presence than in
their absence.
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front 13 - Which of the following treatments would have been the best
control treatment for the experiment?
- A small pool of the lake water maintained in a controlled
laboratory environment
- A different lake that was treated
with sucrose and phosphate
- An untreated section of the
lake
- A section of the lake that was treated with phosphate
but not sucrose
| back 13 - An untreated section of the lake
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front 14 - The average growth rate of the phytoplankton population from
1971 to 1975 in the side of the lake treated with sucrose and
phosphate is closest to which of the following?
- 6,000 (mg/m3)/year
- 1,000 (mg/m3)/year
- 125
(mg/m3)/year
- 1,500 (mg/m3)/year
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front 15 - Which of the following was most likely a direct consequence of
the addition of phosphate to the lake?
- The amount of energy available to consumers in the lake
increased
- The amount of biomass in the first trophic level
decreased.
- The amount of energy available to producers in the
lake increased.
- The amount of biomass in the second trophic
level decreased.
| back 15 - The amount of energy available to consumers in the lake
increased
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