PLANTS AND NITROGEN

Question 1

The complex pattern of nitrogen exchange between these three pools is known as the

Answer 1

nitrogen cycle

Question 2

In the process of decomposition, organic nitrogen is converted to ammonia by a variety of microorganisms.

Answer 2

ammonification

Question 3

These two groups are known as nitrifying bacteria and the result of their activities

Answer 3

nitrification

Question 4

Nitrite is further oxidized to nitrate by members of the genus

Answer 4

nitrobacter

Question 5

In taking up nitrate from the soil, plants must compete with bacteria known as

Answer 5

denitrifiers

Question 6

these bacteria reduce nitrate to dinitrogen

Answer 6

denitrification

Question 7

The process of reducing dinitrogen
to ammonia is known as

Answer 7

nitrogen fixation

Question 8

Nitrogen fixation is a prokaryote domain; because only prokaryote organisms have the enzyme complex, called _________, that catalyses the reduction of dinitrogen to ammonia

Answer 8

dinitrogenase

Question 9

Prokaryotes that fix nitrogen

Answer 9

nitrogen fixers

Question 10

presence of very low oxygen partial pressures

Answer 10

microaerobic

Question 11

In symbiotic associations the plant is identified as the

Answer 11

host

Question 12

the microbial partner is known as
the

Answer 12

microsymbiont

Question 13

Rhizobiwn, Bradyrhizobium, or
Azorhizobium. Collectively, these organisms are referred to as

Answer 13

rhizobia

Question 14

most common form of symbiotic association results in the formation of enlarged,
multicellular structures on the root

Answer 14

nodules

Question 15

Rhizobiwn, Bradyrhizobium, or
Azorhizobium. Collectively, these organisms are referred
to as

Answer 15

rhizobia

Question 16

movement toward a chemical stimulant

Answer 16

positive chemotaxis

Question 17

which include the red, blue, and purple
pigments of leaves and floral petals as well as a number of other important plant products

Answer 17

flavonoids

Question 18

tubular intrusion into the cell

Answer 18

infection thread

Question 19

bacteria cease dividing, enlarge, and differentiate into specialized nitrogen-fixing cells

Answer 19

bacteroids

Question 20

bacteroids remain surrounded by a membrane

Answer 20

peribacteroid membrane

Question 21

time to reduce activity by one-half

Answer 21

half-life

Question 22

At least ________ are required
for each molecule of dinitrogen reduced; two for each electron transferred

Answer 22

16 ATP

Question 23

The nitrogen-fixing cells of the cyanobacteria are specialized cells

Answer 23

heterocysts

Question 24

In legume nodules, the oxygen supply is regulated to a large extent by an oxygen-binding protein

Answer 24

leghemoglobin

Question 25

are transiently associated with the protein and are themselves changed in the reaction

Answer 25

coenzymes

Question 26

nonprotein cofactors more or less permanently associated with the enzyme protein

Answer 26

prosthetic groups

Question 27

unfolding of the enzyme protein

Answer 27

thermal denaturation

Question 28

A variety of ions or molecules may combine with an enzyme in such a way that it reduces the catalytic activity of the enzyme.

Answer 28

inhibitors