Lecture 18 - nitrogen fixation stuff

Question 1

what is a lichen

Answer 1

combo of fungus and algae/cyanobacteria living in symbiosis

Question 2

what do both components of the lichen provide

Answer 2

Alga provides sugars

Fungus protects alga from desiccation

Question 3

How might lichens act as indiactors

Answer 3

Some are sensitive to air pollution
So if they die then indicator of air pollution

Question 4

How come they are usually primary colonisers

Answer 4

found in harsh conditions so they are usually the first there e.g. On rocks, tree barks, roofs

Question 5

what family of plants fix N from atmoaphere

Answer 5

fabaceae
Aka legumes

Question 6

What allows n fixation to occur in fabaceae

Answer 6

mutualistic bacteria in the roots

Question 7

What two type of bact are in roots of fabaceae

Answer 7

alpha proteobact
Bets proteobact

Question 8

What two type of bact are in roots of fabaceae

Answer 8

alpha proteobact
Bets proteobact

Question 9

What enzyme allows n to be fixed

Answer 9

nitrogenase

Question 10

What does n fixation produce

Answer 10

ammonia and h2

Question 11

how does the plant prevent bacteria cheating

Answer 11

plant control oxygen supply to nodules where the bact live
So it rewards bacterial growth by giving the nodules oxy

Question 12

What are mycorrhizas

Answer 12

Mutuslistic associatkon between plant roots and soi fungi
Similar to lichens, but plants and not alage

Question 13

What does the plant get from the fungi in mycorrhizas

Answer 13

soil derived nutrients e.g. Nitrogen and phosphorus

Question 14

What doe the fungi get from the plant

Answer 14

Carbom

Question 15

how many plants % form mychorrizal relationship with fungi

Answer 15

90%

Question 16

What type of plant can’t provide fungus with crbon

Answer 16

Non photosynthetic orchids
So these take carbons from fungi which have taken it from another plant

Question 17

What structure in arbuscular mycrrihiza allow more uptake of nutrients

Answer 17

fungi have extra radical mycelium extending unto the soil

Question 18

How long arbusucules last

Answer 18

5-15 days
Usually when plant needs lots nutrients

Question 19

What type of plants are arbuscular mycorrhizas usually foundin

Answer 19

angiosperms
Gymnosperms
Pteridophytes
Bryophytes

Question 20

How much of land flora do ectomycorrihizal host plants make up

Answer 20

3%
Mostly woody planta

Question 21

How can we experimentall detect carbon flow into fungi

Answer 21

radioactive carbon
Can se ~30% carbon goes into fungi

Question 22

What experiment used to see how much P the fungi consumes form the plant

Answer 22

mesh experiment
In the mesh that fungi was allowed to pass through, P levels in soil were low cuz fungi used it all

Question 23

how do plants uptake inorganic mtter

Answer 23

free living microbes in soil convert organic into inorganic that the plant uptakes
but remember this is not as good as the organic uptake from the fungi that goes directly to plant