SAT II Biology E : Communities and Populations

Study concepts, example questions & explanations for SAT II Biology E

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Example Questions

Example Question #1 : Communities And Populations

R-strategists are known for all of the following except __________.

Possible Answers:

large offspring number

long gestation

low parental investment

small body size

high mortality of young

Correct answer:

long gestation

Explanation:

R-strategists are known for producing large numbers of offspring, though few live to maturity. This is a result of low parental investment, competition, etc. Despite such a large number of offspring, the gestation period for these species is generally shorter than that of K-strategists. For instance, the gestation period of mice is much shorter than the nine months seen in humans.

Example Question #1 : Communities And Populations

Which of the following is not true about an ecosystem?

Possible Answers:

Ecosystems can be terrestrial or aquatic. 

An ecosystem is made up of interactions between multiple species.

Only internal processes control and impact the ecosystem.

An ecosystem describes the biotic and abiotic factors of the environment interacting.

An ecosystem is not static: it can change over time.

Correct answer:

Only internal processes control and impact the ecosystem.

Explanation:

External process also affect the ecosystem. For example, climate is a very important external factor that will affect temperature and precipitation within the ecosystem.

Example Question #2 : Communities And Populations

Which of the following is NOT an abiotic factor?

Possible Answers:

precipitation

temperature

vegetation

humidity

elevation

Correct answer:

vegetation

Explanation:

Abiotic factors are the non-living components of an ecosystem. Biotic factors are living things, such as vegetation (the correct answer because it is the only living thing among the answer choices and therefore NOT abiotic).

Example Question #4 : Communities And Populations

Which of the following is not generally a characteristic of an organism that is a k-strategist?

Possible Answers:

Reproduction at a late age

Large body size

Slow maturation

Efficient use of energy

Short life span

Correct answer:

Short life span

Explanation:

"k" and "r" refer to two different reproductive strategies. K-strategists tend to occupy a more stable environment and have a larger body size as adults and at birth, fewer offspring, longer life spans, more efficient use of energy, later age of reproduction, slower maturation, more parental care, and longer gestation times. The question asked which characteristic is not generally true of k-strategists, and the correct answer is "shorter life spans," which describes r-strategists instead.

Example Question #5 : Communities And Populations

Which of the following is NOT an example of a density-dependent factor?

Possible Answers:

Predation

Natural disasters

Competition

Parasitism

Disease

Correct answer:

Natural disasters

Explanation:

Density-dependent factors are factors that affect population growth only when the population reaches a certain level, and are strongest in a large, dense population and weakest in small, scattered populations. Disease, parasitism, competition, and predation all vary with population density. Natural disasters are the one choice that are density-independent, meaning they affect all populations similarly regardless of size/density.

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