AP Biology Practice Test: Unit 8 — Ecology

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Question 1

Which of the following environmental issues has the most impact on the distribution of local and global ecosystems over time?

A	Global warming
B	Biodiversity
C	Acid rain
D	Habitat fragmentation

Question 1 Explanation:

The correct answer is (A). The most important factor limiting the geographic range for plants and animals is climate. Global warming shifts the climate around the globe, and thus will influence the distribution of ecosystems.

Question 2

In the 1950s, scientists began observing a decline in the populations of certain bird species such as pelicans, ospreys and eagles. They found an accumulation of DDT in the tissues of the birds, which interfered with calcium deposits in their eggshells, rendering them weak. When the birds attempted to incubate their eggs, they cracked and the embryos died. DDT was applied to control insects in the 1940s.

What process describes how the DDT became toxic in the top predators of the ecosystem a decade after it was applied?

A	The greenhouse effect
B	The law of conservation of mass
C	Eutrophication
D	Biological magnification

Question 2 Explanation:

The correct answer is (D). Biological magnification is the process by which toxins accumulate, becoming more concentrated, as they move up the food chain.

Question 3

When a glacier retreats what is left behind is rock that has been scrubbed clean of all life and soil. Through time, the newly revealed land will be recolonized through the process of:

A	Primary succession
B	Secondary succession
C	Tertiary succession
D	Intermediate disturbance

Question 3 Explanation:

The correct answer is (A). Primary succession takes place after a disturbance has left a terrestrial community devoid of all life and viable soil. Secondary succession leaves the soil intact.

Question 4

Which of the following offers the best explanation of the island equilibrium model proposed by MacArthur and Wilson?

A	Over time, an island’s geology will remain stable.
B	Over time, the rate of immigration and the rate of species extinction become equal and stabilize the population and the number of species will correlate with the island’s size and its distance from the mainland.
C	The size of the island will be the primary determinate of the number of predators the island can support.
D	The location of the island will be the primary determinate of the types of predators the island can support.

Question 4 Explanation:

The correct answer is (B). MacArthur and Wilson proposed that the rate of species extinction will equal the rate of immigration, and the number of species at this equilibrium point can be correlated to the size of the island and its distance from the mainland.

Question 5

If a mother graylag goose’s egg rolls out of its nest, the goose will instinctively roll it back with its beak. Interestingly, if the egg is removed from the goose while it is rolling it back to the nest, the goose will continue the behavior as if moving an imaginary egg. In addition, the goose will also try to retrieve other objects that are shaped like an egg, such as a golf ball, and return them to them to the next.

This is an example of what type of behavior?

A	Kinesis
B	Taxis
C	Fixed Action Pattern
D	Habituation

Question 5 Explanation:

The correct answer is (C). A fixed action pattern is a sequence of instinctive actions that, one begun, are typically carried out to completion.

Question 6

Prairie dogs give an alarm call when a suspected predator is nearby. When prairie dog habitats are located near trails used by humans or located in a zoo, they do not give alarm calls each time a human approaches.

This is an example of what type of behavior?

A	Imprinting
B	Spatial learning
C	Associative learning
D	Habituation

Question 6 Explanation:

The correct answer is (D). Habituation occurs when an animal stops responding to a stimulus that conveys little or no new information. This allows an animal’s nervous system to more important signals, such as those that signal the presence of a mate, food or serious threat.

Question 7

Which of the following is a selfless behavior exhibited by some animals living in a close-knit society, where some animals behave in such a way as to reduce their individual fitness but increase the overall fitness of the population?

A	Altruism
B	Inclusive fitness
C	Social learning
D	Agonistic behavior

Question 7 Explanation:

The correct answer is (A). Altruism is exhibited when an animal in a close-knit group, such as prairie dogs, seemingly puts its survival on the line to benefit the group. For example, a prairie dog will “sound the alarm” when an intruder is nearby to alert its colony. This draws attention to the individual sounding the alarm and could lead to death of the individual but save the others in the colony.

Question 8

When an adult vervet monkey sees an eagle, it gives a specific alarm call (a short-double-syllabled cough). They are able to distinguish among eagle species and only sound the alarm for the two species that eat vervets. Infant vervet monkeys, however, give very undiscriminating alarm calls. They sound an alarm call every time they see a bird. As they get older, their accuracy improves. Infant vervet monkeys probably learn how to give the right call by observing other group members and receiving social confirmation. For example, if the infant gives the call and there is in fact a predator, the other group members will also give the alarm call. But if the organism is not a threat, the other members of the group remain silent.

The type of learning illustrated by this example is known as:

A	Reciprocal altruism
B	Operant conditioning
C	Imprinting
D	Social learning

Question 8 Explanation:

The correct answer is (D). Reciprocal altruism is when animals behave altruistically towards nonrelatives. Operant conditioning is trial and error learning. Imprinting involves a specific stage in life during which long-lasting behavioral response is formed to a particular individual or object. Social learning involves learning by observing others.

Question 9

A study conducted on bumblebees in Colorado showed how different species of Bombus complete for nectar. Different species appeared to have adaptations that allowed them to exploit different species of plants based on the corolla length of the plant’s flowers. Different bumblebee species preferred different corollas in accordance with the length of their proboscis. In other words, bee species with a long proboscis preferred flowers with a long corolla, and bee species with a short proboscis preferred flowers with a short corolla.

This is an example of:

A	Resource partitioning
B	Competitive exclusion
C	Character displacement
D	Relative abundance

Question 9 Explanation:

The correct answer is (A). Resource partitioning allows similar species to coexist by using different sets of resources.

Question 10

Late in the 19^th century, hundreds of wolves roamed the Greater Yellowstone Ecosystem. The wolves were eradicated because it was feared that they would devastate the abundant herds of elk and bison, as well as local livestock. The removal of the wolves from the ecosystem caused a cascade of events that changed the entire Greater Yellowstone Ecosystem. First, the elk populations exploded, which led to greater competition between elk herds competing for food. Their overgrazing reduced the size of populations of other species which rely on the plants for survival, such as fish, beaver and songbirds. Additionally, stream banks eroded as a result of the overgrazing, allowing soil and sediments to enter the water. Realizing their mistake, the US government began reintroducing wolves to the Greater Yellowstone Ecosystem, and many of these problems have begun to reverse.

The importance of the wolf species in the ecosystem has led conservation biologists to consider the wolves to be a(n):

A	Invasive species
B	Foundation species
C	Keystone species
D	Mutualistic species

Question 10 Explanation:

The correct answer is (C). Keystones species are those that exert such a strong control on community structure that if they are removed from the ecosystem, there will be dramatic negative impacts.

Question 11

Use the diagram below to answer question 11:

A sea turtle lays approximately 100 eggs at a time, yet on average only one of the eggs will survive to adulthood. Which type of survivorship curve represents a sea turtle population?

A	Type I
B	Type II
C	Type III
D	Types II and III

Question 11 Explanation:

The correct answer is (C). Organisms with Type III survivorship curves experience high early mortality.

Question 12

Interactions between populations can be described as promoting the fitness of a population, having a negative impact on the fitness of a population, or having no impact on the fitness of a population. Which of the following interactions describes one in which one population benefits and the other is unaffected?

A	Parasitism
B	Commensalism
C	Competition
D	Mutualism

Question 12 Explanation:

The correct answer is (B). In a commensalism one member of the pair benefits and the other member of the pair is unaffected. For example, epiphytes are plants that grow on the upper reaches of other plants. Doing so allows the epiphyte access to sunlight. The epiphyte obtains water and nutrients from the air. The tree upon which the epiphyte grows remains unaffected.

Question 13

Use the diagram below to answer questions 13–15:

Which line represents a population of organisms with a highest maximum growth rate increase?

A	A
B	B
C	C
D	D

Question 13 Explanation:

The correct answer is (B). Line B grows exponentially faster than the other lines.

Question 14

Which line represents a population’s carrying capacity (K)?

A	A
B	B
C	C
D	D

Question 14 Explanation:

The correct answer is (A). Carrying capacity represents the maximum population size that a particular environment can sustain.

Question 15

What does Line C represent?

A	Exponential growth
B	Zero population growth
C	Geometric population growth
D	Logistic population growth

Question 15 Explanation:

The correct answer is (D). Logistic population growth model indicates that population growth increase will reach zero as the population reaches carrying capacity.

Question 16

The relationship between cleaner fish and the fish they clean is best described as:

A	Predation
B	Competition
C	Mutualism
D	Commensalism

Question 16 Explanation:

The correct answer is (C). Mutualism describes a relationship in which both interacting members benefit. In this example, the cleaner fish feed on the parasites that are on their clients and their clients are healthier for having the parasites removed.

Question 17

The loss of a predator population from a community can lead to an explosion of prey populations, allowing for intense competition between these species for resources. The result will be a drastic change in community structure. What name is given to a species that plays such a key role in maintaining community structure?

A	Dominant species
B	Apex species
C	Top species
D	Keystone species

Question 17 Explanation:

The correct answer is (D). Keystone species play a major role in maintaining community structure. Often, keystone species are predators. With the loss of their predator prey populations can explode and compete with each other and strip the community of the resources needed for the survival of the prey population(s).

Question 18

If you are ill with a bacterial infection and take antibiotics, the antibiotic will kill the harmful bacteria in your body. You will start feeling better and you may be tempted to stop taking the antibiotics before you finish the prescription. If you do stop taking the antibiotics, a small population of bacteria could survive. This small population of bacteria may have allele frequencies different from the bacteria that perished early in the antibiotic regimen. The remaining population can continue to live in your body and cause problems, but the population of bacteria will not be as genetically diverse.

This phenomenon is referred to as:

A	Bacteria resistance
B	Relative fitness
C	Disruptive selection
D	Bottleneck Effect

Question 18 Explanation:

The correct answer is (D). The bottleneck effect occurs when there is a sudden change in the environment that drastically reduces the size of the population. Because of the reduced population, certain alleles may be overrepresented in the surviving organisms. This will eventually affect the gene pool.

Question 19

If you were late to biology class, and the instructor was discussing hyphae, chitin and mycelium, what could you assume was the topic for the day’s discussion?

A	Protists
B	Prokaryotic cells
C	Fungi
D	Insects

Question 19 Explanation:

The correct answer is (C). Hyphae (filaments forming the body of fungi), chitin (found in fungal cell walls) and mycelium (feeding network fungi) are all parts of fungi.

Question 20

Which of the following applies to biogeography?

A	Humans have ear muscles which are no longer functional.
B	The Galapagos finches are all similar to one another.
C	The forelimb (arm) of a bat and that of a human have a large number of similarities.
D	The wing of a bat and the wing of a bird both play a role in flight.

Question 20 Explanation:

The correct answer is (B). Biogeography is the study of the geographic distribution of species.

Question 21

Differences in variation between populations living in separate locations is referred to as:

A	Geographic isolation
B	Geographic variation
C	Genetic drift
D	The founder effect

Question 21 Explanation:

The correct answer is (B). Geographic variation occurs when there are differences in the genetic composition of separate populations.

Question 22

What it the ultimate source of new alleles in a population?

A	Genetic drift
B	Bottleneck effect
C	Founder effect
D	Mutations

Question 22 Explanation:

The correct answer is (D). A change in the nucleotide sequence of an organism’s DNA can create new alleles.

Question 23

Warmer climates, adequate rainfall and the older age of tropical communities has resulted in:

A	Greater species diversity in tropical communities than in polar and temperate communities
B	Less predation in tropical communities
C	Greater pouching in tropical communities
D	Less mutations

Question 23 Explanation:

The correct answer is (A). Biodiversity favors warmer climates with adequate rainfall. Also, tropical communities have had more opportunities to experience speciation because the growing season is longer and it has not experienced biological setbacks such as glaciations.

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