Chapter 28

Question 1

Biogeochemical cycling

Answer 1

sum of the microbial, physical, and chemical processes that drive the flow of elements

Question 2

Abiotic processes

Answer 2

nonliving (that is , erosion)

Question 3

Biotic processes

Answer 3

also called nutrient cycling

Question 4

Mineralization

Answer 4

decomposition of organic matter to simpler,
inorganic compounds

Question 5

Immobilization

Answer 5

nutrients converted into biomass become
temporarily unavailable for nutrient cycling

Question 6

what are important in mineralizing
immobilized organic compounds?

Answer 6

Saprophytes and predators

Question 7

The Carbon cycle

Answer 7

Carbon is continuously transformed from one form to another

Question 8

What is the first part of the C cycle?

Answer 8

Plants and microbes fix C

Question 9

What is the second phase of the C cycle?

Answer 9

CO2 can be reduced anaerobically to methane (CH4).
Methane is oxidized aerobically by bacteria
or anaerobically by archaea

Question 10

where is methane found?

Answer 10

sediments found in rice paddies, ruminant animals, coal mines, sewage treatment plants, landfills, and marshes.

Question 11

what effects the degradation of organic matter?

Answer 11

*Oxidation-reduction potential.
* Availability of competing nutrients.
* Abiotic conditions.
* pH, temperature, O2, and osmic
conditions.
* Microbial community present

Question 12

what affects the final products that accumulate when organic substrates have been processed and mineralized by microorganisms

Answer 12

oxygen availability

Question 13

what are the final products in oxic conditions?

Answer 13

oxidized accumulate (nitrate, sulfate, CO2)

Question 14

What are the final products of anoxic conditions?

Answer 14

reduced accumulate (ammonium, sulfide, methane)

Question 15

What is lignin?

Answer 15

plant polysaccharides-
Microorganisms secrete hydrolytic enzymes that degrade lignin.
* Only contain carbon, hydrogen, and oxygen.

Question 16

Liebig’s law of the minimum

Answer 16

The nutrient that is insufficient for maximal growth is said to be limiting

Question 17

What is N an essential component of?

Answer 17

DNA, RNA, and proteins (meaning all organisms need N to live and grow)

Question 18

Nitrogen cycle

Answer 18

Nitrogen exists in redox states from -3 to+5.
* electron acceptors in anaerobic respiration or as electron donors in chemolithotrophy

Question 19

N fixation

Answer 19

Reduction of inorganic N2 to Ammonia (NH3) using nitrogenases.
* Carried out by some bacteria and archaea.
* Can be carried out under both oxic and anoxic conditions.

Question 20

nitrification

Answer 20

ammonium (NH4+) donates e-
NH4+ –> NO2- –>NO3-

Question 21

Assimilatory nitrate reduction

Answer 21

NO3− is reduced and incorporated into microbial and plant cell biomass

Question 22

Dissimilatory nitrate reduction

Answer 22

when nitrate is fully reduced to dinitrogen gas (N2), nitrogen is removed from ecosystem and returned to atmosphere

Question 23

N mineralization

Answer 23

decay of dead things (manure, etc. )
done by decomposers (fungi and bacteria)
N from the dead org. converted to ammonium (NH4+)

Question 24

anammox reaction?
anaerobic or areobic?

Answer 24

anaerobic reaction
NH4+ donor with NO2- as final e- acceptor
shortcut to N2 gas without having to go through nitrate

Question 25

what is the phosphorous cycle

Answer 25

essential component of DNA part of ATP and ADP forms phospholipids in cell membranes forms bones, teeth, and shells COMES FROM PHOSPHATE-CONTAINING ROCKS Phosphonates (C—P bond) are the organic form and source for phosphorus for marine microorganisms SLOWEST

Question 26

sulfur cycle

Answer 26

- Sulfur (S) enters the atmosphere as hydrogen sulfide (H2S) during fossil fuel combustion, volcanic eruptions, gas exchange at ocean surfaces, and decomposition - SO2 and water vapor makes H2SO4 ( a weak sulfuric acid), which is then carried to Earth in rainfall - Sulfur in soluble form is taken up by plant roots and incorporated into amino acids such as cysteine. It then travels through the food chain and is eventually released through decomposition. - Sulfate ions (SO4 2- ) dissolved in water are common in plant tissue - Animals, including humans, rely on sulfur from plants they eat

Question 27

Assimilatory sulfate reduction

Answer 27

Reduction of sulfate for use in amino acid and protein biosynthesis

Question 28

dissimilatory sulfate reduction

Answer 28

The use of sulfate as a terminal electron acceptor

Question 29

where is sulfur found

Answer 29

The earths crust (lithosphere)

Question 30

what is sulfur a component of/ needed for?

Answer 30

most proteins and some vitamins needed for the 3D structure of DNA

Question 31

iron cycle

Answer 31

Iron essential in small quantities Often exists in the wrong oxidation state for uptake

Question 32

Siderophore

Answer 32

bind Fe3+ facilitating its transport into the cell, where it is reduced to Fe2+

Question 33

Dissimilatory reduction Fe3+

Answer 33

Fe3+ serves as terminal electron acceptor during anaerobic respiration. * Wide range of bacteria and archaea

Question 34

Manganese cycle

Answer 34

Transform reduced Mn2+ to oxidized MnO2. * Diverse bacteria use Mn2+ as e- donor with O or nitrate as terminal e- acceptor.

Question 35

Mercury cycle

Answer 35

Anaerobic bacteria, Desulfovibrio, methylate mercury accumulations into forms that are accumulated in the food chain

Question 36

Nitrogen Oxide Greenhouse Gases

Answer 36

NO and N2O referred to as “Nox” Have about 280 times the global warming potential of CO2

Question 37

eutrophication

Answer 37

disruption of an ecosystem by buildup of runoff and the accumulation of nutrients