ecology

Biologists have discovered that the beluga whales of Canada’s St. Lawrence River have the highest rates of cancer among animals. What is MOST likely the reason for this high incidence of cancer in these whales?

• chemical and pollutant runoff into the ocean

• average temperatures increased in the region

• depletion of natural prey from the ecosystem

• increased levels of carbon dioxide in the atmosphere

Which biome has the MOST vegetation?

• grassland

• forest

• tundra

• desert

The human population is increasing every day. How does this increase in population affect the natural resources that maintain humans?

• It increases the supply of resources.

• It decreases the amount of resources.

• It results in less demand for resources.

• It improves the quality of the resources.

Most of the trash in the United States is currently disposed of in one of three ways:

32.5% is recycled or composted

12.5% is incinerated

55% is put into landfills

• increases in recycling and incineration and a decrease in landfill use

• an increase in recycling and decreases in incineration and landfill use

• decreases in recycling and landfill use and an increase in incineration

• a decrease in recycling and increases in incineration and landfill use

Can Earth’s human population increase indefinitely?

• yes, even though resources are finite

• yes, because resources are infinite

• no, even though resources are infinite

• no, because resources are finite

The carrying capacity of a region is affected by both density-dependent factors and density-independent factors. Which is a density-independent factor?

• food

• shelter

• disease

• temperature

As human populations increase, more shelter is needed. Increasing shelter often requires making a trade-off with another resource. In which case is a food resource decreased to increase a shelter resource?

• Farmland is converted into house lots.

• Old-growth timber is cut to build houses.

• Corn is made into ethanol for cars instead of food.

• Wind power generated on farmland provides electricity for a factory.

What will MOST likely happen to a stable ecosystem when a population of animals exceeds the ecosystem’s carrying capacity?

• The ecosystem will improve.

• The ecosystem will degrade.

• The ecosystem will change type.

• The ecosystem will remain unchanged.

What is the carrying capacity of an ecosystem?

• the total number of organisms alive at the same time in an ecosystem

• the minimum number of individuals needed to have balance in an ecosystem

• the total number of individuals, living and dead, that have been supported by an ecosystem

• the maximum number of individuals that an ecosystem can support without harming the ecosystem

The graph below shows a change in an area’s carrying capacity for humans over hundreds of years. What MOST likely happened at Points 1 and 2?

• a drought at Point 1, and a technological advance at Point 2

• a technological advance at Point 1, and a drought at Point 2

• technological advances at Points 1 and 2

• droughts at Points 1 and 2