humus

Question 1

what are the other three big categories that humans and earthworms can’t digest

Answer 1

cellulose, hemicellulose, and lignin

too large to dissolve in water

Question 2

fungi and bacteria have soft or rigid cell walls

Answer 2

rigid

Question 3

can fungi and bacteria fo phagocytosis

Answer 3

no- they have walls

Question 4

what is depolymerization in terms of fungi and bacteria and such

Answer 4

digestion

Question 5

if you chop up polymers and dissolve it in water what will happen

Answer 5

it will be digested

Question 6

greater nitrogen content leads to faster or slower degredation

Answer 6

faster

Question 7

which is degraded faster- proteins or carbohydrates

Answer 7

protiens

Question 8

factors that increase the likelyhood that an enzyme digests a polymer into soluble oligomers

Answer 8

all monomers are the same

backbone within molecule made out of same monomers

linkages between monomers all the same

H bonding between polymers absent

Question 9

oligopeptide

Answer 9

a little piece of a digested protien

Question 10

what are the bonds between amino acid monomers that comprimise a protien

Answer 10

CO-NH

Question 11

do bugs like oligopeptides

Answer 11

yes- they are easy to digest because a protease enzyme cuts the peptide bonds

Question 12

xyloglucans

Answer 12

most abundant hemicellulose in primary cell wall of plants

backbone of glucose monomers linked by identical linkages

Question 13

TF if an enzyme can cut through enough identical linkages, the xyloglucan should be soluble

Answer 13

T- breaking down the size due to identical bonds

Question 14

cellulose properties

Answer 14

All monomers same- glucose

all linkages identical- B1,4

Occurs in bunches

Question 15

can enzymes easily digest cellulose

Answer 15

no because it occurs in bunches

Question 16

what keeps cellulose together

Answer 16

H Bonds

Question 17

what do fungi and bacteria prefer, cellulose or lignin

Answer 17

cellulose

Question 18

how is lignin polymerized

Answer 18

random linkages

Question 19

is lignin easy to digest

Answer 19

no- random linkages, linkages can’t be hydrolyzed

Question 20

how is lignin formed

Answer 20

plant has soup of lignin monomers

free radicals catalyze spontaneously at whatever position the linkage hits

New monomer now has free radical and will now go hunting to pair their unpaired electron, which will result in chain after chain after chain

Question 21

how is polyethylene created

Answer 21

through ethylene monomers and spontaneous random linkages

Question 22

how are humic substances created (polymer wise)q

Answer 22

random linkages like polyethylene and lignin

Question 23

do proteins, starches, and lipids rot fast or slow

Answer 23

fast- worms can digest (people can too!)

Question 24

do hemicellulose and cellulose decompose fast or slow

Answer 24

slow

Question 25

who decomposes hemicellulose and cellulose

Answer 25

microbes

Question 26

What substance is the most degradation resistant

Answer 26

lignin

Question 27

what type pf enzymes can chop up lignin

Answer 27

peroxidases and white rot fungi

Question 28

TF how enzymes depolymerize the lignin creates a free radical

Answer 28

T

Question 29

TF the free radical that enzymes create during lignin depolymerization remain free radicals

Answer 29

F, this will catalyze the repolymerization of lignin monomers + almost anything else organic that happens to be how humic substances are formed

Question 30

is there more lignin in leafy plant tissue or woody plant tissue

Answer 30

woody

Question 31

what is typically with lignin in a plant cell (making it nearly undigestable)

Answer 31

cellulose and hemicellulose of woody tissue

Question 32

TF lignin if wrapped around tube of cellulose

Answer 32

T- defense mechanism

Question 33

TF humic substances and fresh plant residue is the same thing

Answer 33

F, humic substances are the digested versions of plant residue

Question 34

how do humic substances form

Answer 34

randomly assembled like lignin

Question 35

what type of rings are abundant in lignin

Answer 35

benzene rings

Question 36

two types of things to decompose

Answer 36

greens and browns

Question 37

greens- nitrogen cellulose lignin

Answer 37

high nitrogen low cellulose low lignin

Question 38

do greens rot fast

Answer 38

yes

Question 39

do greens leave a lot of humus

Answer 39

no

Question 40

browns- nitrogen lignin

Answer 40

High lignin low nitrogen

Question 41

do browns rot fast

Answer 41

no

Question 42

As browns are depolymerized, part of their carbon skeletons become randomly assembled and turned into highly desireable humic substances TF

Answer 42

T

Question 43

If a plant residue has a high C:N ratio, is it a brown or green

Answer 43

brown- low N

Question 44

If a plant residue has a low C:N ratio, is it a brown or green

Answer 44

green- high N

Question 45

does humus have a high C:N ratio

Answer 45

no

Question 46

for annual crops, does the C:N ratio increase or decrease through the growing season

Answer 46

decrease- more lignin over time. More brown mass with more growing

Question 47

do residues of crops become more or less able to decompose with age

Answer 47

less

Question 48

if you add straw to your soil, the microebes will suck all of the __ out of the soil and incorporate it into their biomass

Answer 48

Nitrogen

Question 49

IF you add leafy greens to your soil, it will rot at high speeds and liberate ________-- into the soil for the next crop

Answer 49

nitrogen

Question 50

green stuff will leave more or less humus

Answer 50

less, unless brown is added

Question 51

TF nematodes eat bacteria and fungi

Answer 51

T

Question 52

Do nematodes release nitrogen from the bacteria

Answer 52

yes

Question 53

polyphenols

Answer 53

compounds containing benzene rings with multiple -OH groups attached

Question 54

what are polyphenols good for for plants

Answer 54

defense against pathogenic fungi and insects

Question 55

do polyphenols make plants harder to decompose

Answer 55

yes if present at high levels

Question 56

mineralization*

Answer 56

conversion of any element from an organic to inorganic form

Question 57

If microbes convert nitrogen in soil to NH4+, is this immobilization

Answer 57

NO mineralization organic -> inorganic

Question 58

immobilization

Answer 58

conversion of an element from an inorganic to an organic form

Question 59

What is the opposite of immobilization

Answer 59

mineralization

Question 60

immobilization or mineralization : plants take up N from soil and convert it into protiens

Answer 60

immobilization inorg to org

Question 61

List some factors that would increase soil organic matter levels

Answer 61

more residues per year cooler temp moister soil more clay appropriate N fertilization no till cover crops replacing inorganic N sources with organic N sources

Question 62

how do cooler temps lead to more organic matter

Answer 62

slows microbial destruction of humus plants are less thirsty- same amt of water supports more biomass

Question 63

how does moister soil lead to more organic matter

Answer 63

soggy soil has more anerobic volume which means slower destruction of humus

Question 64

how does more clay lead to more organic matter

Answer 64

clay particles shield humus particles from microbes

Question 65

how does appropriate levels of N fertilizationa ffect the organic matter

Answer 65

excessive fert- microbes accelerate desctruction too little- less plant biomass