Week15 L3: Plant-Microbe Interactions - NITROGEN

Question 1

Why are minerals to important?

Answer 1

Make up enzymes, biological membranes, amino acids, protein, enzymes and co-enzymes.
Part of the biological processes in the plant to complete its lifestyle.

Question 2

What is the difference between macronutrients and micronutrients? (2 divisions of nutrients)

Answer 2

macronutrients need a higher conc of, more likely to be deficient due to their larger amount.

Question 3

What does photodeficiecy harm in plants?

Answer 3

plants will not be able to photosynthesise

Question 4

How can farmers see what their pant is deficient in?

Answer 4

leaf discolouring

Question 5

What is the major limiting nutrient in crop production?

Answer 5

nitrogen

Question 6

What form of N can plants uptake?

Answer 6

N2 to nitrate and ammonium

Question 7

What is the conversion of di-nitrogen to a form plants can uptake?

Answer 7

nitrogen fixation

Question 8

What is the process of making synthetic nitrogen fertilisers?

Answer 8

industrial fixation

Question 9

How much of the population rely on industrial fixation of nitrogen? (synthetic nitrogen)

Answer 9

50%

Question 10

What are the issues with nitrogen fertilisation?

Answer 10

cost
major pollutants (nitrous oxide)
algal bloom

Question 11

What are the problems when synthetic fertiliser is added to crops? and example of where?

Answer 11

algal bloom
leek into water and algae will grow exponentially to cover the water (pond) green, contamination.
run-off into gulf of Mexico.

Overuse can harm the environment. fertilizer application produced greenhouse gases e.g. nitrous oxide and pollutes waterways.

Question 12

How many molecules does biological nitrogen fixation process? Biological nitrogen fixation.

Answer 12

per 1 molecule of atmospheric nitrogen it requires 16ATP to fix… very costly

Question 13

What is the enzyme involved in atmospheric nitrogen conversion?

Answer 13

nitrogenase

Question 14

What is BNF?

Answer 14

biological nitrogen fixation

Question 15

What is plant symbiosis?

Answer 15

describing any relationship or interaction between two dissimilar organisms.

Question 16

What are the rhizobia?

Answer 16

soil bacteria which colonise the root of plants. in symbiosis with legumes

Question 17

Can legumes recognise any symbionts?

Answer 17

NO, they are very specific

Question 18

Can legumes recognise any symbionts?

Answer 18

NO, they are very specific
Almost a 1:1 RATIO

Specific legume hosts recognise specific symbionts through their node factors

Question 19

What are the 2 types of nodules involved in nitrogen fixation?

Answer 19

determinate andindeterminate

Question 20

What organ does a plant need to carry for biological nitrogen fixation?

Answer 20

Node

Question 21

What is Nitrogen fixation?

Answer 21

the chemical processes by which atmospheric nitrogen is assimilated into organic compounds, especially by certain microorganisms as part of the nitrogen cycle.

Question 22

Can the function of a given plant nutrient be be replaced by another?

Answer 22

NO

Question 23

What are the non-mineral nutrients?

Answer 23

carbon, hydrogen, oxygen

Question 24

What does lack of phosphate look like in a plant?

Answer 24

purple discolouration

discoloured areas wont photosynthesise

Question 25

What an example of a greenhouse gas which fertilizer application produces?

Answer 25

nitrous oxide

Question 26

What is an alternative to industrial nitrogen fixation?

Answer 26

biological fixation

Question 27

What is biological fixation?

Answer 27

Several soil Archaea and Bacteria can fix di-nitrogen as ‘free-living’ organisms or in symbiosis with plants and fungi

Question 28

Why would organisms carry out biological nitrogen fixation?

Answer 28

Something or someone providing them with a source of energy. Otherwise its just a metabolic burden. They would likely be outcompeted by competitors.

Question 29

What is plant-nitrogen fixing microbes symbiosis?

Answer 29

mutually beneficial arrangement

Question 30

How is the plant-nitrogen fixing microbes mutually beneficial? Called Root nodule symbiosis

Answer 30

Trading reduced molecules The plant provides organic carbon derived from photosynthesis, and the bacteria provide fixed nitrogen. Most rhizobia cannot fix nitrogen except in nodules

Question 31

What is the specific plant-microbe interaction?

Answer 31

rhizobia and legumes

Question 32

What are the bacteria which fix nitrogen?

Answer 32

rhizobia

Question 33

What source of nutrients do we get from legumes?

Answer 33

major source of protein

Question 34

What are the 4 steps in the formation of the root nodule? Step1

Answer 34

1. Communication: flavonoid (plant) attracts a specific rhizobia. The nod factors (rhizobia) recognise this signal and identify them as appropriate symbionts. When the rhizobia binds to the specific receptors of the legume, it decides of this is the compatible bacteria. The nodulation process starts. Specific legume hosts recognise specific symbionts through their node factors

Question 35

What are the 4 steps in the formation of the root nodule? Step2

Answer 35

Nod factor perception induces root hair curling. The root hairs trap the rhizobia present in soil. Leads to the formation of the process relating to the nod.

Question 36

What are the 4 steps in the formation of the root nodule? Step3

Answer 36

Infection thread growth Rhizobia must get from the root surface to the inner root tissue where they will populate cells in the incipient nodule. To do this, they grow and divide inside a tubule called an infection thread (the tubule is plant derived and “filled” with bacteria).

Question 37

What are the 4 steps in the formation of the root nodule? Step4

Answer 37

Nodule growth development - Legume nodules form from cell divisions in the root cortex - Rhizobia transform from rod-shaped bacteria into Y-shaped bacteroids - Within the nodule, bacteroids are surrounded by a specialised membrane called symbiosome

Question 38

What are the2 fates of the nodule?

Answer 38

Determinate and indeterminate

Question 39

What are determinate nodules?

Answer 39

more homogeneous and | lose the apical meristem

Question 40

What are indeterminate nodules?

Answer 40

``` They keep growing retain a nodule meristem that is the site of cell proliferation, and have zones of different activities ```