Bio midterm part 2

Which factor(s) can influence continual change in an ecosystem?

• further disturbances

• long-term climate changes

• introduction of nonnative species

• all of the above

Which of the following occurs during the ecological succession of an ecosystem?

• Changes occur that are caused by organisms outside the ecosystem.

• Living organisms modify their environment a little at a time.

• Parts of communities split off to form new communities.

• An ecosystem reaches a final, unchanging stage.

Which is a factor that could interrupt the progress of succession?

• different animals appearing at each stage

• long-term fluctuations in climate

• colonization of surfaces by lichens

• another natural disturbance

The chemistry of aquatic ecosystems is determined by the

• biotic and abiotic factors in the water.

• amount of salts, nutrients, and oxygen dissolved in the water.

• the number of other organisms present in the water.

• amount of rainfall the water receives.

Which one of the following statements is NOT true of freshwater wetlands?

• The water in freshwater wetlands is always brackish.

• Freshwater wetlands include bogs, marshes, and swamps.

• Water may be present near the surface of the soil for part of the year.

• Wetlands are important breeding grounds for migratory birds.

Which is one way a wetland ecosystem differs from a standing-water ecosystem?

• Wetlands are salty, but standing-water ecosystems are fresh.

• Water circulates in a standing-water ecosystem but not in a wetland.

• Water does not always cover a wetland as it does a standing-water ecosystem.

• Wetlands are nesting areas for birds, but standing-water ecosystems are not.

Which of the following is NOT one of the factors that play a role in population growth rate?

• immigration

• death rate

• emigration

• demography

One of the main characteristics of a population is its

• habitat.

• change over time.

• dynamics.

• geographic distribution.

There are 150 Saguaro cactus plants per square kilometer in a certain area of Arizona desert. To which population characteristic does this information refer?

• population density

• growth rate

• geographic distribution

• age structure

What is happening in a population as it decreases?

• The death rate becomes lower than the birthrate.

• The death rate stays the same and the birthrate increases.

• The death rate becomes higher than the birthrate.

• The birthrate and the death rate remain the same.