AP Environmental Science : Ecosystems and Biology

Study concepts, example questions & explanations for AP Environmental Science

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Example Questions

Example Question #361 : Gre Subject Test: Biology

What does a J curve represent on a population growth chart?

Possible Answers:

A species has reached carrying capacity and leveled off due to limited resources

A species has reached the carrying capacity but continues to grow, creating a population explosion and a competition for resources

The maximum point of growth of a species

A species cycles up to carrying capacity, and then back down to the minimum

The correlation between a species and its competitors in a specific niche

Correct answer:

A species has reached the carrying capacity but continues to grow, creating a population explosion and a competition for resources

Explanation:

Population growth can follow either a J curve trend or an S curve trend. A J curve represents exponential, or unrestricted growth. An S curve represents logistic, or restricted, growth and accounts for the carrying capacity of an environment.

In a J curve model, the population will continue to grow even when it has reached capacity. In an S curve model, the population will stagnate and stabilize at a maximum value when capacity is reached.

Example Question #1 : Carrying Capacity

Which is true for clumped distribution patterns? 

Possible Answers:

The distance between individuals in minimized 

It does not affect predation patterns

It is rarely seen in nature

Sources are abundant throughout the environment

Correct answer:

The distance between individuals in minimized 

Explanation:

Clumped distribution patterns localize individuals around scarce resources in environments where they are not equally distributed throughout. The clumping of organisms around these resources attracts predators and makes for easy predation. Because of the scarcity of water in desert, plain and tundra biomes, it is seen in large quantities in nature.  

Example Question #2 : Population Ecology

The maximum number of individuals that a particular habitat can support is called __________.

Possible Answers:

fitness

natural selection

allopatric speciation

carrying capacity

Correct answer:

carrying capacity

Explanation:

The carrying capacity of a certain habitat is the maximum number of individuals that it can support. Population numbers are limited by resources such as space, food, and water. Current estimates of Earth's carrying capacity are around 10 billion. 

Example Question #1 : Population Ecology

A population of dingoes in an Outback region of Australia includes 120 individuals at the start of 2011. At the start of 2012, researchers had observed 18 births and 2 deaths. In addition, they observed 2 individuals immigrating and 3 individuals emigrating. What is the population's net growth rate?

Possible Answers:

12.50%

100%

1.13%

0.13%

88.90%

Correct answer:

12.50%

Explanation:

The population's new size at the start of 2012 was = original population + (births + immigrations) - (deaths + emigrations) = 120 + (18 + 2) - (2 + 3) = 135. Then, the net population growth rate is equal to (net change in population / size of old population) = 15/120 = .125.

Example Question #2 : Population Ecology

K-strategist species exhibit all of the following characteristics except __________.

Possible Answers:

Produces relatively few offspring

Late age of maturity

Relatively long life expectancies

Little time spent by parents raising offspring

Correct answer:

Little time spent by parents raising offspring

Explanation:

Species designated as K-strategists thrive through longevity and have a higher survival rate at birth, but produce far fewer offspring. Examples include elephants and whales. Consider an elephant; it may produce relatively few baby elephants, but these baby elephants each have the potential to live relatively long lives. On the other hand, contrast K-strategists like elephants with r-strategists like rats, locusts, and flies. These species are designated as r-strategists because in contrast, they produce numerous offspring, few of which may survive to adulthood, and each one of which reaches maturity quickly and lives a relatively short life. K-strategists in general spend more time than r-strategists caring for and raising their offspring; they have fewer offspring, so they put more care into ensuring the survival of each one. Contrast elephants with frogs to see this difference; elephants care for their young, while frogs lay their eggs and care for their offspring very little, if at all.

Example Question #2 : Population Ecology

A species designated as "r-strategist" is characterized by all of the following except __________.

Possible Answers:

High reproductive rate

Long life expectancy

Little time spent by parents caring for and raising offspring

Small size

Low age of maturity

Correct answer:

Long life expectancy

Explanation:

Species described as "r-strategist" have a survival strategy of producing large numbers of offspring, a short life expectancy, and typically smaller body sizes. Examples include mice, locusts, and frogs. These species survive by producing lots of offspring, since many individuals don't survive to adulthood.

Example Question #2 : Population Ecology

Which of the following mammals is an "r-selected" species?

Possible Answers:

Blue whale

Human

All of these

Cottontail rabbit

Correct answer:

Cottontail rabbit

Explanation:

R-selected individuals are characterized by the following: early age of sexual maturity, many lifetime reproductive events, large numbers of offspring per event, and minimal parenting. Many of the offspring of r-selected species will die before adulthood. On the other hand, K-selected individuals have only one or few offspring at once and invest larger amounts of time and energy into parenting to ensure survival. The rabbit is the only species listed whose life traits can be categorized as being r-selected.

Example Question #1 : Population Ecology

A brand new country, named Neoland, has a growth rate of 4%. How many years will it take the population of Neoland to double?

Possible Answers:

18 years

2 years

20 years

8 years

Correct answer:

18 years

Explanation:

Use the Rule of 72:

 is rate of growth

 is time (in years) it takes to double

By manipulating the equation to divide 72 by the given growth rate, you can find the number of years it takes for the population to double.

Example Question #1 : Reproductive Patterns And Principles

Which of the following is a false statement regarding genetic mutations?

Possible Answers:

Most mutations are unfavorable to an individual

Mutations are the main source of genetic variation

Mutations are changes in nucleotide subunits

Mutations occur at high rates

Correct answer:

Mutations occur at high rates

Explanation:

Mutations occur at low rates. They are rare and not very common in most individuals. This explains why the process of evolution and adaptation occurs over long periods of time. 

Example Question #11 : Population Ecology

Which of the following factors affect birth rates?

Possible Answers:

Child laborers 

Education level of women

Average marriage age

All of these

Religion

Correct answer:

All of these

Explanation:

The use of child laborers leads to higher birth rates. More children are needed to support families and households. Educating women also decreases birth rates. This is the reason why developing countries tend to have higher birth rates than developed countries. A lower average marriage age leads to an increase in birth rates. Religion can influence birth rates, either raising or lowering (generally it raises the birth rate).

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