AP Biology : Understand biodiversity

Study concepts, example questions & explanations for AP Biology

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Example Questions

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Example Question #1 : Understand Biodiversity

An ecologist is surveying a portion of land that is believed to contain a specific animal species of interest. If the ecologist is measuring the number of this animal species per square meter, what is she measuring?

Possible Answers:

Dispersion

Competition

Carrying capacity

Population density

Population range

Correct answer:

Population density

Explanation:

The population density is the measure of the population per unit area or volume, and may be measured over land or water.

The carrying capacity refers to the maximum number of organisms that can be sustained by the resources of an environment. The range of a population is simply the area over which the population can be found. Dispersion refers to the different regions where a species is found within a given area. Competition is the use of limited resources between multiple members of a population, or multiple species within a niche.

Example Question #2 : Understand Biodiversity

Which of the following factors determine the distribution of the earth's habitats and ecosystems?

I. Air circulation

II. Rainfall

III. Topography

IV. Microbiological factors

V. Reproduction rates

Possible Answers:

I, II, and III

II, IV, and V

I, III, and V

I, II and IV

II, III, IV, and V

Correct answer:

I, II, and III

Explanation:

The earth's habitats and ecosystems are dispersed based on air circulation, rainfall, and topography. For example, when looking at the globe, we may notice that the world's major grasslands are always leeward of major mountain ranges, or that tropical rain forests are located around the equator. Why do grasslands fall on the leeward side of mountain ranges, and tropical rainforests at the equator? As the air travels up the mountain, it condenses and precipitation occurs. Once the air reaches the leeward side, it is dry, resulting in the grasslands and plains. Tropical rainforests are located at the equator, an area that gets constant sunlight and rainfall regardless of the earth's tilt. The dispersion of the earth's habitats and ecosystems is very dependent on such environmental factors.  

Example Question #1 : Understand Biodiversity

Which of the following describes a community?

Possible Answers:

Multiple organisms interacting 

A variety of organisms of the same species living in the same area and interacting 

Abiotic and biotic relationships and interactions in a given area

Food webs created by the food chains of a given area

A group of populations of different species living in the same area and interacting

Correct answer:

A group of populations of different species living in the same area and interacting

Explanation:

A community is a group of populations of different species but live in the same area and interact. Community interactions may display interspecific interactions such as competition, predation, herbivory, symbiosis, or facilitation. A population is a group of organisms of the same species that live together and interact. 

Example Question #4 : Understand Biodiversity

The sea otter plays an important role in controlling the sea urchin population in the Pacific Ocean. While they are not abundant in numbers, they play a vital role. The sea otter is an example of which of the following concepts?

Possible Answers:

Commensalism 

Dominant species

Keystone species

Ecosystem engineers 

Resource partitioning 

Correct answer:

Keystone species

Explanation:

The sea otter is an example of a keystone species. Keystone species are not abundant in the community, however they have a strong control on community structure because their ecological roles are so important. On the other hand, dominant species are those that are most abundant in their communities and have the highest biomass. The dominant species competitively exploits resources and avoid predation, giving them an advantage and allows them to grow large in number. Ecosystem engineers are species that dramatically alter their environment by changing its physical characteristics. 

Example Question #5 : Understand Biodiversity

Two types of mosses grow separately. However, when they are put in the same environment and forced to live together, one of the mosses goes extinct. This is an example of which of the following?

Possible Answers:

Resource partitioning 

Competitive exclusion

Adaptation

Ecological niche

Character displacement

Correct answer:

Competitive exclusion

Explanation:

Competitive exclusion is when an inferior competitor is eliminated. In the moss example, the moss that is able to use resources more efficiently and reproduce quicker will beat out the less competitive moss. An ecological niche is the sum of a species’ use of the biotic and abiotic resources in its environment. Resource partitioning is the differentiation of niches that allows similar species to coexist in a community. If one of the mosses could adapt to use different resources, the two species could coexist together. Character displacement has to do with speciation. It refers to the tendency for character traits to diverge more in sympatric populations rather than allopatric populations.  

Example Question #6 : Understand Biodiversity

Forest 1 has A, B, C, and D trees. There are five A trees, nine B trees, ten C tree, and six D trees. Forest 2 has A, C, and D trees. There are ten A trees, fourteen C trees, and seven D trees. Forest 1 demonstrates __________ over forest 2.  

Possible Answers:

species diversity and species richness

species richness only

species diversity only

species diversity, species richness, and greater biomass

greater biomass only

Correct answer:

species diversity and species richness

Explanation:

Species diversity is the variety of organisms that make up a community. There are two parts of species diversity: species richness and relative abundance. Species richness refers to the number of different species in the community. In this example, forest 1 has greater species richness and diversity over forest 2.  

Example Question #82 : Ecology

A seed that normally plants itself in the countryside is carried by the wind and plants itself in a forest. There, the seed grows and multiplies, competitively excluding many other native plant species. In the forest, this seed is an example of which of the following?

Possible Answers:

Invasive species

Parasitism

Species diversity 

Homologous structures

Herbivory 

Correct answer:

Invasive species

Explanation:

Invasive species are organisms that become established outside their native range. In this example, the seed’s native range is the countryside. However, when it is carried by the wind to the forest (an environment outside its native range), it plants itself and establishes a population there. The seed is an example of an invasive species. 

Example Question #3 : Understand Biodiversity

Which of the following is not considered to be a component of an ecosystem?

Possible Answers:

Limited to one species

Abiotic components

Biotic organisms

Interactions between organisms and the environment

Correct answer:

Limited to one species

Explanation:

Ecosystems are described as a community of organisms and their interactions between themselves and the environment. Ecosystems include abiotic and biotic components of the environment and are not limited to one species.

Example Question #1 : Understand Biodiversity

Which of the following is an internal factor that impacts ecosystems?

Possible Answers:

All of these

Presence of species

Availability of resources

Frequency of disturbances

Correct answer:

All of these

Explanation:

Ecosystems are communities of abiotic and biotic components that interact together in the same environment. Ecosystems are controlled by both internal and external factors. Internal factors that control ecosystems include the availability of limiting resources, species presence, and disturbance.

Example Question #2 : Understand Biodiversity

Which of the following is an external factor that controls ecosystems?

Possible Answers:

Climate

Frequency of disturbances

None of these

Availability of resources

Correct answer:

Climate

Explanation:

Ecosystems are communities of abiotic and biotic components that interact together in the same environment. Ecosystems are controlled by both internal and external factors. External factors that impact ecosystems include but are not limited to the invasion of non-native species, climate, and time.

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