Lecture #3

Question 1

What kind of organisms fix N2?

Answer 1

Only prokaryotes

-Bacteria

Question 2

What is in the Phylum Proteobacteria?

Answer 2

Rhizobium (fixes N2 in nodules of legumes)

Question 3

What is in the Phylum Cyanobacteria?

Answer 3

Nostoc which are in Lichens

Anabaena which lives inside water ferns and fixes N2

Question 4

What is in the Phylum Anctinobacteria?

Answer 4

Frankia which fixes N2 for non-legumes

Question 5

What does the pink in Rhizobium do?

Answer 5

Protects bacterial cells from O2

-Excludes O2 from the N2 fixing process because N2 can’t be fixed in the presence of O2

Question 6

Why does Rhizobium have Leghemoglobin?

Answer 6

To allow the bacterium to keep O2 out of the N2 fixation process
-redirects it

Question 7

What does the Phylum Glomeromycota form?

Answer 7

forms endomycorrhizal associations with most land plants

-Liverworts and angiosperms

Question 8

What is important about the Phylum Ascomycota?

Answer 8

May associate with selected cyanobacteria and or green algae to FORM LICHENS

Question 9

What does the Phylum Basidiomycota form?

Answer 9

Associations with roots of selected vascular plants to form ectomycorrhizae

Question 10

What would happen if theses symbioses hadn’t occurred?

Answer 10

Plants would have remained in the oceans and would have not migrated to land

Question 11

What do endomycorrhizal associations do?

Answer 11

Fungi penetrates root cells

• Fungus goes indie of the root cortical cells of the plant.
• It branches out within the cell in order to maximize the surface area for nutrient exchange
• all branches are surrounded by the plasma membrane, not inside the cytoplasm

Question 12

Why do some fungi form vesicles?

Answer 12

• Mainly just for storage

- Or if the root dies, the vesicles remain to reproduce again

Question 13

What do ectomycorrhizal associations do?

Answer 13

Fungi grow in-between plant root cells

• there is a thick layer of fungus on the outside of the root tip
• fungus explores the soils for water and nutrients and bring it back to the root
• Root tip doesn’t experience the outside world

Question 14

What is a Lichen?

Answer 14

Dual organism

• Symbiosis with a mycobiont which forms the structure and obtained nutrients
• Photobiont (green algae or cyanobacteria) which produces the photosynthetic sugars

Question 15

Are lichens an evolutionary group?

Answer 15

No, they are just a guild

Question 16

What is the mycobiont within a Lichen?

Answer 16

It is the fungus that produces the structure of the lichen and how it gets its nutrients and water

Question 17

What are the 3 different forms of Lichens?

Answer 17

Foliose
Fruticose
Crustose

Question 18

Do lichens reproduce sexually or asexually?

Answer 18

Both

Question 19

What are the possible ways that Lichens reproduce asexually?

Answer 19

• Finger-like structures on the surface (breaks off)
• Small lobes (breaks off)
• SOR, powdery balls are fungal filaments wrapped around the cell (falls off)

Question 20

How can a Lichen reproduce sexually?

Answer 20

There is the sexual part the shoots spores out of it.

• needs an algal partner in order to become a new Lichen
• Produces a lot of spores to increase the chances of coming into contact with and algal partner

Question 21

Where does the sexual reproduction happen within a Lichen?

Answer 21

In the fungus (mycobiont)

Question 22

What are Rhizines?

Answer 22

Root like structures BUT ARE NOT ROOTS

-hold the lichen down

Question 23

What kind of cells contain the spores in order for lichens to reproduce sexually?

Answer 23

Tubular cells

Question 24

Why do Lichens have bright colours?

Answer 24

They are from secondary metabolites which act as sunscreen

Question 25

How does the Lichen sunscreen work?

Answer 25

The algae within the lichen all have photosynthetic limbs, so when the machinery shuts down, it needs the the colour to absorb access energy.

Question 26

Why does the Lichen need the 'sunscreen'?

Answer 26

When its dry/no precipitation, the Lichen does into suspended animation. In order to protect the algae within, the colour is needed to reflect the energy until it becomes wet out when photosynthesis resumes

Question 27

What is a Lichen desert?

Answer 27

An area with no foliose or fruticose lichens

Question 28

What are the 2 causes of Lichen deserts?

Answer 28

1. SO2+H2O--> H2SO4 (sulphuric acid) kills everything | 2. Poor environmental conditions

Question 29

What are lichens sensitive too?

Answer 29

They are sensitive to air pollution and are only sensitive when lichens are wet -fruticose and foliose are the most sensitive

Question 30

What does the term Mycorrhiza refer to?

Answer 30

The association of the structure, not the fungus or the plant

Question 31

Why does fungus make a better root?

Answer 31

They are able to explore lots more soil with little cost

Question 32

What are the 2 types of mycorrhizae?

Answer 32

Endo | Ecto

Question 33

What is the other word for endomycorrhizae?

Answer 33

Arbuscular Mycorrhizae

Question 34

Where would to find the spores of endomycorrhizae?

Answer 34

Soil or dead roots

Question 35

What nutrients do endomycorrhizae deliver?

Answer 35

Phosphorus

Question 36

In what period did we find fossils own endomycorrhizae?

Answer 36

Triassic | 220MYA

Question 37

When was the colonization of plant plants?

Answer 37

400MYA | -colonized close to fresh water

Question 38

What do ectomycorrhizae usually associate with?

Answer 38

Pine, brich oak etc

Question 39

Describe the association between plant and ectomycorrhizae

Answer 39

Hyphae forms a mantle over the root and grows in between cells, never penetrating the cell

Question 40

Do ectomycorrhizae form large sexual fruiting bodies?

Answer 40

Yes, above and below ground

Question 41

Why is it hard for root diseases to affect the plant?

Answer 41

Fungal mitten over the root are covered in antiherbivory compounds and prevent organisms from eating it