AP Environmental Science : Populations and Communities

Study concepts, example questions & explanations for AP Environmental Science

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Example Questions

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Example Question #1 : Ecosystem Development And Relationships

What describes a "stable population?"

Possible Answers:

A population in which member numbers do not fluctuate in a given time period

A population that uses resources in an effective manner, such as resource partitioning

A population in which carrying capacity is well above the current number of individuals

A population in which the offspring have a low mortality rate

A population in which the number of children is approximately the same as the number of reproducing adults

Correct answer:

A population in which the number of children is approximately the same as the number of reproducing adults

Explanation:

A stable population is described as one in which birth rate equals to death rate, and the number of children is about equal to the number of reproducing adults.

Example Question #1 : Ecosystems And Biology

Which term describes all members of a particular species within an ecosystem, found in the same time and space?

Possible Answers:

Organism

Community

Inhabitant

Population

Gene pool

Correct answer:

Population

Explanation:

By definition a population is all persons, plants, or animals inhabiting a specified area. A community is the interacting populations within an ecosystem. A gene pool is the total of all alleles of all genes in a population. The definition of an inhabitant is a person or animal that lives in or occupies a place. An organism is any living thing, plant, or animal. 

Example Question #1 : Populations And Communities

Which of the following choices is best defined as a group of genetically compatible (able to mate) individuals living in the same geographical area.

Possible Answers:

Niche

Community

Population

Species

Correct answer:

Population

Explanation:

Populations consist of individuals of the same species in a common area. Communities are made up of groups of populations of different species within a given geographic range. Last, a niche refers to the specialized role and position that a species has within its environment.

Example Question #3 : Ecosystems And Biology

The Galapagos Islands are famously associated with Charles Darwin. The islands are home to many species that can be found nowhere else in the world; furthermore, some of the Galapagos species are only found on a single island.

Which of the following choices best describes a species that is found in only one area?

Possible Answers:

Adapted

Endemic

 Specialist

None of these

Correct answer:

Endemic

Explanation:

A species is "endemic" when it is found only in one particular location. The flightless cormorant, marine iguana, and Galapagos penguin are all examples of species that are endemic to the Galapagos Islands.

Example Question #4 : Ecosystems And Biology

Which of the following choices correctly ranks the species conservation statuses from least serious to most serious?

Possible Answers:

None of these

Least concerned, near threatened, vulnerable, endangered, extinct

Least concerned, near threatened, endangered, vulnerable, extinct

Extinct, endangered, near threatened, vulnerable, least concerned

Least concerned, vulnerable, near threatened, endangered, extinct

Correct answer:

Least concerned, near threatened, vulnerable, endangered, extinct

Explanation:

Least concerned refers to the lowest risk where species members are abundant. Near threatened means the species is likely to become endangered at some point. Vulnerable means that, in the wild, the species are at high risk for becoming endangered. Endangered is similar to vulnerable, but has a high risk of extinction, not just endangerment. Extinct means there are no more members of the individuals in a species remaining. The correct ranking is as follows: least concerned, near threatened, vulnerable, endangered, and extinct.

Example Question #5 : Ecosystems And Biology

Which of the following is not a direct cause of depletion and premature extinction of wild species?

Possible Answers:

Introduction of an invasive species

Predator and pest control

Population growth

Habitat loss

Pollution

Correct answer:

Population growth

Explanation:

Population growth is an underlying cause of depletion and premature extinction of a wild species, but is not a direct cause. On the other hand, habitat loss is a direct cause of depletion and premature extinction of wild species due to processes like over logging, damming rivers, or urban development. Pollution is a direct cause of extinction in the wild, usually caused as streams, rivers, and oceans are polluted. The introduction of an invasive, nonnative species to an environment can create an unbalanced ecosystem, directly causing extinction of wild species. These invasive species are often harmful and fill niches previously occupied by native species. Increasing predator species in an area can significantly reduce or drive prey species to extinction. Similarly, increasing the use of pesticides and pest controls can directly cause extinction of organisms in the affected ecosystem.

Example Question #6 : Ecosystems And Biology

Which of the following terms refers to a group of organisms that are of the same species?

Possible Answers:

Organism

Population

Ecosystem

Community

Correct answer:

Population

Explanation:

A population is a collecting of individuals from the same species. Populations are a unit of organization that has measurable properties, such as population density and home range. Populations are altered by birth and death, immigration, and emigration. 

Example Question #6 : Ecosystems And Biology

Which of the following models was identified by Richard Levins and describes the connectivity of populations in different habitats within the same landscape? It suggested that individuals migrate from one habitat to another, which moved genes and maintained the health of the species.

Possible Answers:

Metapopulation model

Habitat matrix model

Landscape model

Source-sink model

Correct answer:

Metapopulation model

Explanation:

The correct answer is “metapopulation model.” It describes multiple sub-populations that are connected together in a larger, metapopulation. This is typically shown as patches within a larger landscape. The patches represent sub-populations. Individuals can migrate from one patch to another, but they are all part of the same population.

Example Question #8 : Ecosystem Development And Relationships

Life history traits can be highly variable in a population. Which of the following is not an example of a life history trait?

Possible Answers:

Evenness

Maturity 

Fecundity

Parity 

Correct answer:

Evenness

Explanation:

The correct answer is “evenness.” All the other terms describe life history traits. “Maturity” refers to the age of first reproduction. “Parity” is described as the count of reproduction events. Last, “fecundity” is defined the number of offspring at each reproduction event.

Example Question #7 : Ecosystems And Biology

Which of the following terms describes a species that has a disproportionate effect on its community than would be expected by its overall biomass?

Possible Answers:

Keystone species

Rare species

Dominant species

None of these

Common species

Correct answer:

Keystone species

Explanation:

The correct response is “keystone species.” A keystone species makes up a small portion of community; however, it has a major impact on the community structure despite making up a small percentage of the ecosystem that it inhabits. "Dominant species" have large number and large impacts; thus, this answer choice does not fulfill the disproportionate part of the description. "Common species" and "rare species" both have low impacts on the community structure, so they are poor answer choices. 

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