SAT II Biology E : Communities and Populations
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Example Questions
Example Question #4 : Ecological Principles
R-strategists are known for all of the following except __________.
low parental investment
high mortality of young
small body size
long gestation
large offspring number
long gestation
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 #5 : Ecological Principles
Which of the following is not true about an ecosystem?
An ecosystem is not static: it can change over time.
Only internal processes control and impact the ecosystem.
An ecosystem is made up of interactions between multiple species.
Ecosystems can be terrestrial or aquatic.
An ecosystem describes the biotic and abiotic factors of the environment interacting.
Only internal processes control and impact the ecosystem.
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 #6 : Ecological Principles
Which of the following is NOT an abiotic factor?
precipitation
elevation
humidity
vegetation
temperature
vegetation
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 #7 : Ecological Principles
Which of the following is not generally a characteristic of an organism that is a k-strategist?
Large body size
Short life span
Reproduction at a late age
Slow maturation
Efficient use of energy
Short life span
"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 #8 : Ecological Principles
Which of the following is NOT an example of a density-dependent factor?
Competition
Predation
Disease
Parasitism
Natural disasters
Natural disasters
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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