Unit 7 Review

Which of the following situations contributes to the sustainability of an ecosystem?

• Increase in biodiversity

• Decrease in biodiversity

• Extinction of a population from the ecosystem

• Removal of many populations of organisms

The role of a pioneer species in primary succession is to change a bare habitat into one that is suitable for other organisms. A species that is responsible for primary succession in an ecosystem is most likely able to —

• survive any predator

  photosynthesis

• migrate during the winter

• live at high altitudes

• carry out photosynthesis

Which of the following sequences most likely represents ecological succession on a recently

abandoned wheat field?

• grasses → flowering plants → shrubs → native trees

• native trees → shrubs → flowering plants → grasses

• shrubs → grasses → native trees → flowering plants

• flowering plants → native trees → shrubs → grasses

The more diverse an ecosystem is —

• the more threatened its populations are

• the more similar the species will be

• the more sustainable it is

• the fewer varieties of species are present

A hurricane hits a coastal prairie and destroys the habitat. Years later there is an appearance of

small plants with rapidly spreading roots.

This vegetation describes —

• a microhabitat

• primary succession

• secondary succession

• biodiversity

A flower bed is created at a school so flowers can be planted in the autumn.

Over the summer, the flower bed is ignored.

Which of the following should the students expect to find when they come back to school?

• 
• 
• 
• 

If your local environment begins to turn into a desert, what will most likely happen to the organisms in the environment?

• The populations of organisms currently existing in the environment will increase.

• The populations of organisms currently existing in the environment will not be affected.

• The new desert environment will be unable to support any populations of organisms.

• A different variety of organisms will be supported rather than the ones that currently exist.

• The prairie ecosystem, because fewer organisms eat grass

• The tundra ecosystem, because there is a variety of producers

• The prairie ecosystem, because there are fewer top predators

• The tundra ecosystem, because it has more herbivores

Which statement below best describes how biodiversity contributes to the sustainability of an ecosystem?

• A variety of plant and animal species allows for more survivors of a natural disaster.

• Having more species in an ecosystem allows the human population to increase in size.

• Low biodiversity reduces the competition for resources, which helps native species survive.

• Fewer species in the ecosystem reduces the likelihood that disease spreads through the

  ecosystem

When forest fires destroyed many of the pine trees in Bastrop State Park, the burned areas began secondary succession. What is the role of succession in this example?

• Changing the landscape to be more fire resistant in the future

• Creating new soil by chemical and physical weathering of rocks

• Restoring the ecosystem through grass, shrub, and tree stages

• Opening the land for new uses like farming and raising livestock