REVIEW/STUDY GUIDE FOR ECOLOGY TEST
QUESTIONS STRAIGHT FROM TEST
A researcher is interested in the effects of nitrate and phosphate on plant growth and sets up an experiment in which
groups of five plants are given 1, 2, and 3 grams of nitrate and 1, 2, and 3 grams of phosphate in all
combinations over a period of one month. The researcher measures plant height and weight at the end of
the experiment. What is missing in this experimental design?
a. a control
c. a dependent variable
b. an independent variable
d. a constant
Cougars are predators that often eat weakened or diseased animals. This is a description of the ____ of cougars.
a. habitat
c. niche
b. community
d. none of these
Figure 2-1
Figure 2-3
In the energy pyramid shown in Figure 2-3, which level has the smallest number of organisms?
a. fox
c. grasshoppers
b. birds
d. grass
flea
Figure 2-4
The organism shown in Figure 2-4 is involved in which type of symbiosis?
a. mutualism
b. commensalism
c. parasitism
d. predation
Which process describes nitrogen fixation?
a. animals eat plants containing nitrogen and return it to the soil through urination
b. bacteria take nitrogen from the air and convert it to a form usable by plants
c. organisms die and are decomposed into ammonia in the soil
d. plants take nitrogen from the air and store it in their roots
Which biogeochemical cycle is least dependent on biotic processes?
a. carbon
c. phosphorus
b. nitrogen
d. water
One of the nutrient cycles moves from an atmospheric gaseous form to the soil through both abiotic and biotic
processes, moves through the food web, then is returned to the soil or to the atmosphere. Which cycle fits
this description?
a. carbon
c. phosphorus
b. nitrogen
d. water
Figure 3-1
In Figure 3-1, where will you most likely find the greatest diversity?
a. A
c. C
b. B
d. D
In Figure 3-1, which section would account for a lower number of organisms near the bottom of a pond due to a short
supply of oxygen and sunlight?
a. A
c. C
b. B
d. D
Figure 3-4
Look at the graph in Figure 3-4. What does this graph tell us about this species of plant?
a. Too much sunlight can hurt them.
b. They thrive in a lot of sun.
c. Heat is damaging to them.
d. They need plenty of water.
What would be the best time of the year to plant the organism described in Figure 3-4?
a. winter
c. summer
b. spring
d. fall
A team of ecologists measured the salinity of the water in an estuary at various distances from the river
mouth. They also sampled populations of two species of clam worm, Nereis occidentalis and Neanthes
succinea, at each point. The results are tabulated below.
Table 3-1
Which of the following hypotheses is most valuable in explaining the trends seen in the data?
a. Nereis occidentalis outcompetes Neanthes succinea at salinities under 14‰.
b. Neanthes succinea reproduces most rapidly in areas at least 20 meters from the river
mouth.
c. Both Neanthes succinea and Nereis occidentalis can survive at any salinity.
d. Nereis occidentalis is more resistant to salinity than Neanthes succinea.
If the ecologists were to take a population sample of Neanthes succinea in an area 65 meters from the river mouth
with 30‰ salinity, what do you infer that they would find?
a. 40–50 individuals
b. 10–20 individuals
c. fewer than 5 individuals
d. more than 50 individuals
Compare primary and secondary succession. What is the distinction between them?
a. Primary succession is the sequence of species that become established early in a newly
colonized area, and secondary succession is the sequence of species that move in later.
b. Primary succession is the establishment of a community in an area with no soil, while
secondary succession is the establishment of a new community in an existing ecosystem
that was disturbed.
c. Primary succession is the establishment of a new community in an existing ecosystem that
was disturbed, while secondary succession is the establishment of a community in an area
with no soil.
d. Primary succession is the sequence of plants that colonize a new area, while secondary
succession is the sequence of animals that move in later.
A place at 2º N latitude has an average annual temperature of –6º C. What can you conclude about the environment?
a. It is cold, so it must be in the northern polar region.
b. Nothing can be concluded except the information given.
c. It is at a very high altitude.
d. It must be submerged at the bottom of a deep ocean to be equatorial and so cold.
A flowering plant has seeds that are carried by the wind. Infer the most likely dispersion pattern of the plants that
grow from these seeds.
a. uniform
c. random
b. clumped groups
d. spatial
Which of the following statements is correct?
a. Population size of predators increases when their prey is scarce.
b. Competition for resources is density-independent when food is plentiful.
c. Disease is density-dependent because transmission occurs more easily when a population
is large.
d. A change in average temperature is a density-dependent factor because fewer organisms
can acclimate to variations in temperature.
How does the logistic model of population growth differ from the exponential model?
a. The exponential model shows a restricted growth rate.
b. The logistic model considers the environment’s carrying capacity.
c. The graph of the exponential model is S shaped.
d. The graph of the logistic model has a longer lag phase.
Agriculture led to an increase in the size of the human population. Which of the following was the most important
impact of agriculture on the human population size?
a. It stabilized and increased available food supplies.
b. It made people better able to resist disease.
c. It reduced accidental deaths from hunting.
d. It decreased the negative impacts of storms.
Which of the following methods might be used to decrease the rate of approach to carrying capacity by the developed
world?
a. increase birthrate
b. decrease death rate
c. decrease resource use
d. decrease emigration
Table 5-1 shows the population sizes for 6 different species in four different areas.
Area
Species U
Species V
A
3
7
B
0
C
D
Species W
Species X
Species Y
2
2
2
4
6
8
0
6
6
0
0
2
0
0
2
4
3
11
1
6
0
Table 5-1
Which area in Table 5-1 has the greatest biodiversity?
a. Area A
b. Area B
c. Area C
d. Area D
From Table 5-1, which species has the highest average population size?
a. Species W
c. Species Y
b. Species X
d. Species Z
Species Z
Figure 5-2
What does the graph in Figure 5-2 tell you?
a.
b.
c.
d.
the farther from land, the more biodiversity
the larger the islet, the more biodiversity
islet size and biodiversity are not related
biodiversity decreases with islet size
Figure 5-4
Examine the food web shown in Figure 5-4. What would most likely happen to the organisms in this ecosystem if the
algae began to disappear?
a. The bass population would increase.
b. All of the aquatic organisms would become overpopulated.
c. The dragonfly population would likewise begin to disappear.
d. The fox would begin to starve and be forced to emigrate to another area.
Examine the food web shown in Figure 5-4. The disappearance of which of the following pair of species would result
in the total collapse of the food web?
a. algae and dragonflies
c. dragonflies and foxes
b. algae and elm trees
d. elm trees and bass
Which is an inference?
a. You measure a plant’s height every day for a week.
b. You give a plant the same amount of water every day.
c. Every day for a week, you collect data on a plant’s movement.
d. After watching a plant for a week, you determine it needs more sunlight.
Which best describes the difference between an observation and an inference?
a. You can record an observation; an inference is an idea.
b. You make an inference before you make observations.
c. An observation is a conclusion; an inference is a hypothesis.
d. An observation is based on evidence, an inference is not.
Tasha is testing the effect of blue-colored light on the growth of tomato plants. Which is the independent variable in
this experiment?
a. light color
c. amount of light
b. light intensity
d. temperature of light
Which is the most likely inference Luisa might make after watching the wildlife around her birdfeeder?
a. Ten birds come every morning to feed at her bird feeder.
b. Birds and squirrels compete for the same food sources.
c. Different birds come to the bird feeder each day.
d. Squirrels run very quickly up and down trees.
Which of the following correctly sequences the steps of the scientific method?
a. question, observe, explain, design and conduct experiment, collect and analyze data, report
findings
b. observe, question, make a testable explanation, experiment, collect and analyze data, state
findings
c. form a hypothesis, observe, investigate a testable question, collect and analyze data, state
results
d. design and conduct an investigation based on a testable question, form a hypothesis,
collect data, state findings
Some birds are known as honey guides because they may be followed by humans to wild beehives. When the humans
take honey from the hives, the birds are able to feast on the honey and bees, too. This type of relationship
can best be described as ____.
a. parasitism
c. mutualism
b. commensalism
d. symbiosis
How long are food chains?
a. four steps long
b. three steps long
c. it varies with day length
d. it varies with ecosystem
Which of the following nutrients has only a short-term biogeochemical cycle?
a. carbon
c. oxygen
b. nitrogen
d. phosphorus
If you were dropped off on the North American continent at a latitude of 40º N, which of the following climate zones
would you discover there?
a. polar
c. temperate
b. tropical
d. arctic
If precipitation on a tropical savanna increased from 100 to 200 centimeters per year but temperature remained the
same, what biome would replace the savanna?
a. tropical rain forest
c. tropical seasonal forest
b. temperate forest
d. temperate rain forest
Which of the following effects on the climate would you infer would result from an increase in altitude?
a. the same as an increase in precipitation
b. the same as a decrease in precipitation
c. the same as a decrease in latitude
d. the same as an increase in latitude
How would you classify a biome having forest with broad-leaf evergreen trees, mosses, and orchids, 20–25º C
temperatures, and where the >200 cm of rainfall per year is seasonal?
a. tropical seasonal forest
c. tropical rain forest
b. tropical savanna
d. temperate woodland
Figure 5-3
What effect did the loss of species B have on species A and D in Figure 5-3?
a. it caused the populations of A and D to decrease
b. it caused the populations of A and D to increase
c. it caused the populations of A and D to become extinct
d. it had no effect on the populations of A and D
A scientist is investigating a new drug that will cure the common cold. The scientist should give the
____________________ group a sugar pill, rather than the drug.
The three major causes of human deaths throughout recorded history are war, famine, and
____________________.
The different environmental conditions that occur along the boundaries of an ecosystem are described by
ecologists as ____________________.
In an investigation on the effect of exercise on breathing rate, the breathing rate is the
____________________ variable.
In an experiment testing the effect of loud noises on a person’s reaction time, Sarah uses different
volumes of a particular song when testing the time it takes a person to catch a falling ruler. The
____________________ variable is the reaction time.
To explain and show how the amount of living material at each trophic level of a food chain changes, you
could use a pyramid of ____________________.
Plants return liquid water to the atmosphere through a process called ____________________.
A previously rapidly growing population of green tree frogs in the city park has suddenly leveled off, and
is presently neither increasing or decreasing in numbers. You can probably infer that the tree frog
population has reached its ____________________.
Sugar dissolves in, or mixes completely with, water. The solubility of a substance in water is determined
by measuring the maximum amount of the substance that dissolves in a given amount of water at a given
temperature. HYPOTHESIS: The solubility of sugar in water increases as the temperature of the water
decreases. Identify the independent and dependent variables.
Explain why biomes do not encircle Earth in simple belts reflecting the effect of latitude on climate.
An electromagnet can be made by wrapping insulated wire around an iron nail and connecting the ends of
the wire to a 6-volt battery. HYPOTHESIS: Increasing the number of coils of wire wrapped around the
nail increases the strength of the electromagnet, as measured by the number of paper clips the magnet can
pick up. Identify the independent and dependent variables.
Compare and contrast a food web and a food chain.
List and describe the various levels of biological organization that may be studied by an ecologist.
Figure 2-6
Use the diagram in Figure 2-6 to complete Table 2-1. Classify each member of the food web as autotroph
or heterotroph, and identify the heterotrophs as herbivores, carnivores, or omnivores.
Table 2-1
Autotrophs
Heterotrophs
Herbivore, carnivore,
or omnivore
A student grew a yeast culture on sterilized nutrient medium in a closed dish for five days. Each day, she
took the same size sample from the dish and placed it on a special slide used for counting microorganisms
(see the top half of Figure 4-2). She examined the samples under a microscope and drew the illustrations
of her observations over the course of the investigation. Each dot represents ten yeast cells.
Figure 4-2
Which graph (A, B, or C in the bottom half of Figure 4-2) best pictures the growth of the student's yeast
population?
Referring to Figure 4-2, what steps could the student take to ensure the accuracy of her results?
In Figure 4-2, how could the carrying capacity of the culture dish be increased?
In Figure 4-2, how could you estimate the population size of the yeast in Day 3 without counting all the
dots in all the squares?
What problem was this student investigating in Figure 4-2?
Why did the student use sterilized medium and keep the dish closed? Refer to Figure 4-2.
Why can exotic species be a problem in conservation biology?
A scientist wrote the following summary of her observations:
Milkweed is a plant commonly found throughout fields and pastures and along roadsides in eastern
and central North America. It gets its name from the milky white sap that oozes when the plant is broken
or cut. Milkweed plants bloom in June and July. When fertilized, the flowers form large seedpods that
open in the fall. The following observations were taken from a scientist's field study of milkweed plants
from spring through fall.
In the summer, the sugary nectar secreted by the milkweed's flowers attracts many bees, butterflies,
moths, and a variety of smaller insects that carry away pollen when they depart. Milkweed nectar seems
to be the major source of nutrition for several species of small moths, flies, mosquitoes, and ants.
Monarch butterflies, which visit in large numbers, lay their eggs on milkweed plants, and the hatching
caterpillars feed on the leaves. As fall approaches, milkweed bugs begin to attack the developing seeds,
and milkweed beetles eat the foliage.
Aphids, which suck milkweed sap, are found throughout the year. Crab spiders do not feed on the
plant itself, but rather on most of the insects that visit the plant. In the two to three weeks while the
milkweed plants are in bloom, successful adult female crab spiders may increase ten times in mass before
laying their eggs on the inner surface of leaves. Some species of flies and wasps, which feed on crab
spider eggs, visit the plants periodically. Harvestmen, also known as "daddy longlegs," recover the
remains left by predators.
Based on the scientist's observations, formulate two possible hypotheses about the effects of crab spiders
on the survival of the milkweed plant.
Did this scientist perform quantitative or descriptive research?
Levels of atmospheric carbon dioxide have increased and are correlated with global increases in
temperature. In response, scientists are attempting to quantify carbon emissions from all sources. Cleared
forest land was hypothesized to be a source of carbon dioxide entering the atmosphere along with carbon
from burning fossil fuels. The following data (K. Brown, 1992, Carbon Sequestration and Storage in
Tropical Forests) compare soil carbon quantities from three types of forest as the land is converted to
agricultural uses. Here the terms “open” and “closed” refer to the canopy of the forest—a closed canopy
lets little light reach the forest floor.
Table 3-3
Analyze the data and conclude whether clearing forest land is contributing to global warming or not.
Briefly explain your reasoning.
Figure 5-6
Examine the desert food web shown in Figure 5-6. Describe the possible consequences of the extinction
of the snake.
Discuss whether you think food webs change over time (for example, in the course of a year) and why.
Suggest examples to back up your arguments.
Table 4-1
Evaluate the data in Table 4-1, and summarize the general trends shown in birthrates and death rates for
the years 1900–1950. Include in your summary whether the population is decreasing or increasing and
why. Relate the birthrates and death rates.
The return of the soldiers from WWII (1945–1947) caused an exception to the general trend in 1950.
What is the exception? Explain.
A new entity has been found. Scientists are trying to determine if it is living or non-living. The entity has
only the following characteristics: uses oxygen, requires energy, can move, and gets bigger over time.
Evaluate the preceding characteristics of the substance and decide if it is alive or not. Defend your
answer.
What are the possible outcomes of the extinction of a species in a biological community? Use the
structure of a food web to explain what might happen in the event of an extinction.