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Evolution of Plants > Lecture #3 > Flashcards

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?

A

Both

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
Q

How does the Lichen sunscreen work?

A

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
Q

Why does the Lichen need the ‘sunscreen’?

A

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
Q

What is a Lichen desert?

A

An area with no foliose or fruticose lichens

28
Q

What are the 2 causes of Lichen deserts?

A
  1. SO2+H2O–> H2SO4 (sulphuric acid) kills everything

2. Poor environmental conditions

29
Q

What are lichens sensitive too?

A

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

30
Q

What does the term Mycorrhiza refer to?

A

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

31
Q

Why does fungus make a better root?

A

They are able to explore lots more soil with little cost

32
Q

What are the 2 types of mycorrhizae?

A

Endo

Ecto

33
Q

What is the other word for endomycorrhizae?

A

Arbuscular Mycorrhizae

34
Q

Where would to find the spores of endomycorrhizae?

A

Soil or dead roots

35
Q

What nutrients do endomycorrhizae deliver?

A

Phosphorus

36
Q

In what period did we find fossils own endomycorrhizae?

A

Triassic

220MYA

37
Q

When was the colonization of plant plants?

A

400MYA

-colonized close to fresh water

38
Q

What do ectomycorrhizae usually associate with?

A

Pine, brich oak etc

39
Q

Describe the association between plant and ectomycorrhizae

A

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

40
Q

Do ectomycorrhizae form large sexual fruiting bodies?

A

Yes, above and below ground

41
Q

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

A

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

Evolution of Plants (12 decks)

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