Exam 31: Microorganisms in Terrestrial Ecosystems

Enzymes,once released from plant and animal cells,can remain present and function independent of the organisms that synthesized them.

In the process of forming a root nodule,species of Rhizobium differentiate to form a type of cell called a

In bog soils,the decomposition rate of lignin-cellulose complexes is accelerated by the water-logged,predominately anoxic conditions.

An important bacterial mediated process that occurs on the surface of plant roots is called _________ nitrogen fixation.

The common building block of ___________ is the phenylpropene unit,which consists of a hydroxylated six-carbon aromatic benzene ring and a three-carbon linear side chain.

A common resident of the rhizosphere that can enhance plant growth is

The surface of a plant root is called the __________.

Oxygen diffuses through water approximately 4,000 times faster than through dry soil.

One of the most common bacterial genera cultured from plant leaves is

An average gram of forest soil contains about

A substance that promotes binding of Rhizobium to plant root hairs is called a __________ factor.

Protozoa in soils utilize bacteria as a nutrient source.

Agrobacterium has the ability to infect plants and produce tumor-like growths.

The ____________ mycorrhizae are the most common type of mycorrhizae.

Which of the following statements is correct?

Rhizobium and Bradyrhizobium are significant contributors to which process when engaged in a symbiotic relationship with leguminous plants?

Except for a shallow surface layer,the earth's crust is known to be free of microorganisms.

The plant leaf surface is called the rhizosphere.

Mycorrhizae are formed by the association of plants with

Recent studies indicate that active prokaryotic assemblages are present in high-temperature oil reservoirs,including such genera as