Lecture #3 Flashcards

1
Q

What kind of organisms fix N2?

A

Only prokaryotes

-Bacteria

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2
Q

What is in the Phylum Proteobacteria?

A

Rhizobium (fixes N2 in nodules of legumes)

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3
Q

What is in the Phylum Cyanobacteria?

A

Nostoc which are in Lichens

Anabaena which lives inside water ferns and fixes N2

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4
Q

What is in the Phylum Anctinobacteria?

A

Frankia which fixes N2 for non-legumes

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5
Q

What does the pink in Rhizobium do?

A

Protects bacterial cells from O2

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

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6
Q

Why does Rhizobium have Leghemoglobin?

A

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

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7
Q

What does the Phylum Glomeromycota form?

A

forms endomycorrhizal associations with most land plants

-Liverworts and angiosperms

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8
Q

What is important about the Phylum Ascomycota?

A

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

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9
Q

What does the Phylum Basidiomycota form?

A

Associations with roots of selected vascular plants to form ectomycorrhizae

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10
Q

What would happen if theses symbioses hadn’t occurred?

A

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

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11
Q

What do endomycorrhizal associations do?

A

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
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12
Q

Why do some fungi form vesicles?

A
  • Mainly just for storage

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

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13
Q

What do ectomycorrhizal associations do?

A

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
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14
Q

What is a Lichen?

A

Dual organism

  • Symbiosis with a mycobiont which forms the structure and obtained nutrients
  • Photobiont (green algae or cyanobacteria) which produces the photosynthetic sugars
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15
Q

Are lichens an evolutionary group?

A

No, they are just a guild

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16
Q

What is the mycobiont within a Lichen?

A

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

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17
Q

What are the 3 different forms of Lichens?

A

Foliose
Fruticose
Crustose

18
Q

Do lichens reproduce sexually or asexually?

19
Q

What are the possible ways that Lichens reproduce asexually?

A
  • Finger-like structures on the surface (breaks off)
  • Small lobes (breaks off)
  • SOR, powdery balls are fungal filaments wrapped around the cell (falls off)
20
Q

How can a Lichen reproduce sexually?

A

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
21
Q

Where does the sexual reproduction happen within a Lichen?

A

In the fungus (mycobiont)

22
Q

What are Rhizines?

A

Root like structures BUT ARE NOT ROOTS

-hold the lichen down

23
Q

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

A

Tubular cells

24
Q

Why do Lichens have bright colours?

A

They are from secondary metabolites which act as sunscreen

25
How does the Lichen sunscreen work?
The algae within the lichen all have photosynthetic limbs, so when the machinery shuts down, it needs the the colour to absorb access energy.
26
Why does the Lichen need the 'sunscreen'?
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
27
What is a Lichen desert?
An area with no foliose or fruticose lichens
28
What are the 2 causes of Lichen deserts?
1. SO2+H2O--> H2SO4 (sulphuric acid) kills everything | 2. Poor environmental conditions
29
What are lichens sensitive too?
They are sensitive to air pollution and are only sensitive when lichens are wet -fruticose and foliose are the most sensitive
30
What does the term Mycorrhiza refer to?
The association of the structure, not the fungus or the plant
31
Why does fungus make a better root?
They are able to explore lots more soil with little cost
32
What are the 2 types of mycorrhizae?
Endo | Ecto
33
What is the other word for endomycorrhizae?
Arbuscular Mycorrhizae
34
Where would to find the spores of endomycorrhizae?
Soil or dead roots
35
What nutrients do endomycorrhizae deliver?
Phosphorus
36
In what period did we find fossils own endomycorrhizae?
Triassic | 220MYA
37
When was the colonization of plant plants?
400MYA | -colonized close to fresh water
38
What do ectomycorrhizae usually associate with?
Pine, brich oak etc
39
Describe the association between plant and ectomycorrhizae
Hyphae forms a mantle over the root and grows in between cells, never penetrating the cell
40
Do ectomycorrhizae form large sexual fruiting bodies?
Yes, above and below ground
41
Why is it hard for root diseases to affect the plant?
Fungal mitten over the root are covered in antiherbivory compounds and prevent organisms from eating it