Interactions - Decomposers/Detritivores

Question 1

How do these differ from carnivores?

Answer 1

They have no control on the abundance of their resource consumed, depending on resource rates of other forces driving death.

Question 2

What are the two types of saprotroph?

Answer 2

Decomposers
Detritivores

Question 3

Saprophyte

Answer 3

An organism living on dead or decaying organic matter.

Question 4

Immobilization

Answer 4

The process where nitrate/ammonium are taken up by soil organisms thus becoming unavailable to crops

Question 5

Decomposition

Answer 5

Gradual disintegration of dead OM by physical/biological agencies

Question 6

Where may dead organic matter derive frmo?

Answer 6

Shedding, leaf litter, faeces, death of an organism…

Question 7

Rhizosphere

Answer 7

The region goverend by interactions between plants and organisms now in close association with the roots

Question 8

Phyllosphere

Answer 8

Aboveground plant prts colonized by mcorbial communities

Question 9

What supports the phyllosphere?

Answer 9

Exudation of plant tissue soluble sugars supports bacterial growth

Question 10

What is the first step in decomposition process?

Answer 10

Prokaryotic colonization and autolysis by enzymes in the dead tissue, breaking down macromolecules into soluble forms.

Question 11

How do bacteria break down material?

Answer 11

Leach soluble materials like AA and sugars, where then ‘enzyme reliant material’ is digested by specialised organisms

Question 12

R Selection

Answer 12

These have high growth rates, exploiting less crowded ecological niches, and produce many offspring

Question 13

Examples of enzyme-reliant material?

Answer 13

Lignin, Chitin, Celullose and Keratin

Question 14

What is early decomposition dominated by?

Answer 14

Aerobic conditions, prokaryotes utilising O2 for sugar breakdown with CO2 byproducts

Question 15

What follows prokaryotic sugar decomposition?

Answer 15

Fermenntation breakdown sugars with alcohol formation, usually lowering pH of soils due to acid production

Question 16

Examples of anoxic habitats?

Answer 16

Waterlogged soils, estuaries and lake sediments.

Question 17

Example of resource change with decomposition?

Answer 17

Pectins and hemicellulose by beta-glucosidase, then cellulose by endocellulases, whilst lignin constnat throughout by laccase

Question 18

How are fungi and Bacteria measured?

Answer 18

Levels of ergosterol and phospholipid fatty acids.

Question 19

How do decomposers change over time?

Answer 19

First eight months of leaf litter decomposition by varying fungi, with complete decomp dependent on bacteria and archae and fungi

Question 20

How is rate of decomposition regulated by organisms?

Answer 20

Early slowed by microbivores due to recruiting faster than decomposers, then sensecent hyphae cropping later faciltiates decomposition

Question 21

Classes of organisms?

Answer 21

Microfauna
Mesofauna
Megafauna

Question 22

Function of fauna proceeding degradation?

Answer 22

Shred remains, potential of soil structure development with detritus re-distribution.

Question 23

What is an example of plant biochemistry variablity among ecosystems?

Answer 23

Decomposition occurs quicker closer to parent trees

Question 24

What is rate of decomposition dependent on most?

Answer 24

Quality of litter, like magnesium, tannin and water saturation capacty(tannins being toxic, magnesiums essential and water adsorption controlling fauna.

Question 25

What are the most prominent organic compounds of dead leaf?

Answer 25

Cellulose and Lignin, of which animal herbivores typically cannot degrade

Question 26

How may animals facilitate cellulose breakdown?

Answer 26

Symbiotic bacterial communities within the stomach

Question 27

Importance of coprophagous detritivores?

Answer 27

Increase decomposition rate and thus nutrient release into soil.