SAT II Biology E : Ecology

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

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Example Questions

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Example Question #1 : Ecological Principles

Which of the following is not an abiotic component of an ecosystem?

Possible Answers:

Humidity

Temperature

Minerals

Wind speed

Molds

Correct answer:

Molds

Explanation:

Abiotic factors are non-living and molds are living.

Example Question #1 : Ecological Principles

An ecosystem includes which of the following?

Possible Answers:

Communities and populations

Communities only

Biomes and populations

Populations only

Biomes, communities, and populations

Correct answer:

Communities and populations

Explanation:

Ecosystems are composed of communities and communities are composed of populations. A biome is a larger unit than an ecosystem, as it includes multiple ecosystems.

Example Question #1 : Biomes, Habitats, And Niches

1. Largest biome in the world

2. Short, wet summers and long, cold winters

3. Flora consists of mostly coniferous trees

The given statements most closely describe which biome?

Possible Answers:

Chaparral

Tundra

Alpine

Taiga

Deciduous forest

Correct answer:

Taiga

Explanation:

The taiga biome is the largest biome in the world and is characterized by short, rainy summers coupled with long, freezing winters. Due to its extremely cold temperatures, the taiga's flora or plant life consists of mostly coniferous trees that can survive on the scarce nutrients available in the cold climate of the biome. In contrast, the tundra is frozen year-round and permafrost prevents any trees from growing. Deciduous forests, as the name suggests, sports mainly deciduous trees as its plant life. The alpine biome consists mostly of the areas right below the snow lines of mountains and is generally dry year-round. The chaparral is a relatively small biome that is characterized as being mostly hot and dry year-round, with mild winters.

Example Question #11 : Ecology

Which of the following biomes is dominated by grasses and herbaceous plants, with some trees and shrubs, and characterized by seasonal rains, a pronounced dry season, and often large migratory mammals?

Possible Answers:

Savanna

Tropical rainforest

Desert

Tundra

Temperate deciduous forest

Correct answer:

Savanna

Explanation:

The characteristics listed describe a savanna. Deserts can also have pronounced periods of rain and dryness but are not dominated by grasses and not populated by large migratory animals. Tropical rainforests and deciduous forests are dominated by trees and tundras tend to be colder and may not receive much rainfall, but often have moist soil due to low evaporation rates.

Example Question #1 : Communities And Populations

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

Possible Answers:

long gestation

small body size

high mortality of young

large offspring number

low parental investment

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 #2 : Communities And Populations

Which of the following is not true about an ecosystem?

Possible Answers:

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.

Ecosystems can be terrestrial or aquatic. 

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 #3 : Communities And Populations

Which of the following is NOT an abiotic factor?

Possible Answers:

temperature

elevation

precipitation

vegetation

humidity

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:

Short life span

Slow maturation

Efficient use of energy

Reproduction at a late age

Large body size

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:

Disease

Predation

Parasitism

Competition

Natural disasters

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.

Example Question #11 : Ecology

A new volcanic island forms in the Pacific Ocean. Over time, soil forms on the island, grasses grow, shrubs appear, birds nest on the island, and the island is no longer a barren rock. This is an example of which of the following?

Possible Answers:

A climax community because the community changed and grew more complex.

A population bottleneck because the population on the island has to be very limited due to the nature of islands.

Ecological succession because the structure and composition of the community has changed over time.

Evolution because the species on the island changed over time.

Correct answer:

Ecological succession because the structure and composition of the community has changed over time.

Explanation:

This is an example of ecological succession. While climax community may seem like a reasonable answer, the text describes the entire process from barren rock onwards and does not specifically state that new species are no longer appearing on the island and that the community is stable. Evolution occurs within a species, and while the species on the island may change, the species themselves are not described as changing. This question mentions nothing about genetics, thus we cannot determine whether or not a population bottleneck (a reduction in population that is sudden and reduces genetic diversity) is occurring and we have no evidence that one is.

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