Question 1

In a stable ecosystem, the number of predators is greater than the number of prey.

Accepted Answer

In a stable ecosystem, the number of prey is greater than the number of predators. This helps to maintain a balance in the ecosystem and prevent overconsumption of resources. A higher number of predators compared to prey would lead to a decline in the predator population due to lack of food, which, in turn, would lead to an increase in the prey population. This cycle continues until a balance is reached where the number of prey can support a stable predator population.

Question 2

Woodpeckers and squirrels both nest in tree cavities. This is an example of interspecific competition.

Accepted Answer

Both woodpeckers and squirrels require tree cavities for nesting, which means they compete with each other for limited resources. This is a clear example of interspecific competition.

Question 3

The biotic portion of an ecosystem includes the plants, animals, and water.

Accepted Answer

The biotic portion of an ecosystem includes the living components such as plants and animals, but not abiotic components like water, which are part of the ecosystem's non-living or physical environment.

Question 4

The next time you need to mow the grass, you can excuse yourself, saying that by mowing you are helping to maintain a man- made

Accepted Answer

Mowing the grass prevents the natural progression to a climax community, maintaining a subclimax community, which is a stage in ecological succession that is maintained by regular disturbances like mowing.

Question 5

A certain species of animal represents just 3% of the biomass in its ecosystem. We might classify this as a keystone species if its removal

Accepted Answer

A keystone species has a disproportionately large impact on its ecosystem relative to its biomass. If its removal causes a significant decline in plant community diversity, it indicates its crucial role in maintaining ecosystem structure and function.

Question 6

Intraspecific competition limits population size.

Accepted Answer

Intraspecific competition refers to competition between individuals of the same species for resources such as food, water, and space. This competition can reduce the availability of these resources and ultimately limit the population size of the species.

Question 7

Some toxic animals are brightly colored, as a means of warning others of their danger.

Accepted Answer

This is known as aposematic coloration and is common in toxic or venomous animals such as poison dart frogs, coral snakes, and certain species of insects.

Question 8

When a community like the tallgrass prairie is maintained by recurring disturbances such as periodic fires set by Native Americans or by lightning, a community exists.

Accepted Answer

A subclimax community is maintained by recurring disturbances, preventing it from reaching a stable climax community.

Question 9

What ecological process causes a lake to change into a marsh over a long period of time?

Accepted Answer

Succession is the ecological process where a body of water like a lake gradually fills with sediment and organic matter, eventually transforming into a marsh or terrestrial ecosystem over time.

Question 10

Birds follow a herd of water buffalo to catch insects that are disturbed as the large herbivores walk through the grass. When large predators are near, the birds fly into the air and make warning calls. Who are the birds warning?

Accepted Answer

The birds are warning the water buffalo so they can avoid attack from predators.

Question 11

A species that plays a major role in determining the structure of its ecological community is

Accepted Answer

A keystone species has a disproportionately large impact on its environment relative to its abundance, playing a critical role in maintaining the structure of an ecological community.

Question 12

Why is the African elephant considered a keystone species?

Accepted Answer

The African elephant is considered a keystone species because its activities, such as tree felling and seed dispersal, significantly shape the ecosystem. Removing them would lead to drastic changes in the ecological structure.

Question 13

In a process called coevolution, two species exert natural selection pressures on each other.

Accepted Answer

In coevolution, two species exert natural selection pressures on each other, which can lead to adaptations and changes in both species over time.

Question 14

A storm strips an island in Lake Superior down to bare rock. The first organisms to recolonize the island are most likely

Accepted Answer

Lichens are pioneer species that can colonize bare rock surfaces, as they are capable of surviving in harsh conditions and contribute to soil formation.

Question 15

Invasive species outcompete native species because they lack predators and have high reproductive rates.

Accepted Answer

Invasive species often lack natural predators and may have adaptations that give them a competitive advantage over native species, such as high reproductive rates, efficient use of resources, and tolerance for a wider range of environmental conditions.

Question 16

The first community that forms on bare rock often has organisms such as

Accepted Answer

Lichens and mosses are pioneer species that can colonize bare rock, initiating the process of primary succession by breaking down the rock and creating soil for other plants.

Question 17

In mutualistic interactions, one species is harmed and one benefits.

Accepted Answer

In mutualistic interactions, both species benefit and neither is harmed.

Question 18

In most environments, two or more organisms occupy identical niches.

Accepted Answer

In most environments, organisms have adapted to occupy different niches to minimize competition and increase chances of survival. However, there are situations where organisms may occupy identical niches but typically this is rare and short-lived.

Question 19

Succession that begins on bare rock after glaciers have passed, or on newly formed volcanic islands, is

Accepted Answer

The answer of Succession that begins on bare rock after...

Question 20

After a forested area such as a national forest is clear- cut, what type of succession occurs?

Accepted Answer

Secondary succession occurs in areas where a disturbance has destroyed a community but left the soil intact, such as after clear-cutting in a forest.

Quiz 28: Community Interactions