Exam 37: Communities and Ecosystems

Nitrogen fixing bacteria in the roots of soybeans help provide a source of nitrogen to the plants,and in exchange obtain food from the plants.Which reaction can these bacteria catalyze?

The virus in this study ____.

After taking antibiotics and developing a yeast infection in the genitourinary tract,the yeast infection lessens as the microbes that normally are present reestablish themselves.The reason for the lessening of the yeast infection is explained by:

In a process called bioremediation,chemicals accumulate in the highest trophic levels within a food chain.

Biomagnification usually happens for chemicals that:

Lichens live on the side of trees,getting better access to the sun,with no apparent harm to the tree.This is an example of:

When Steller sea lions and harbor seals became less plentiful,orcas began using sea otters as a primary food source.

Species that are the first to colonize an area are termed:

Walleye pike are which of the following?

A relationship between different species in which one species lives in or on another is:

The total amount of energy trapped by the autotrophs of an ecosystem is called:

An organism's _____________________ is its position in the food chain,relative to the ecosystem's energy source.

Organisms that obtain their energy from producers or other consumers are:

Resource partitioning allows only a single species to use a resource.

How was the virus detected?

The decline of the sea otter population in the Pacific Northwest has been attributed to:

Walleye pike tend to live in deep waters and feed at night.Northern pike live in shallower waters and feed all day.Which of the following best explain these differences?

The species that appear in a climax community usually are short-lived,early maturing,r-selected species that are strong competitors in a stable environment.

A type of symbiosis in which one member of the relationship benefits with no effect on the other is:

The tidal zones in which the barnacles Balanus and Cthalamus thrive when both species are present illustrate the principle of: