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Semester 2 Exams > ah ze fungiiiiiiiiii > Flashcards

ah ze fungiiiiiiiiii Flashcards

1
Q

what part of the fungi lies underneath the soil?

A

the mycelium

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2
Q

3 ways in which fungo are like animals

A

not producers
no photosynthesis
chitin not cellulose e.g. like insects

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3
Q

3 ways in which fungi are like plants

A

grow on a substrate
non motile
cell walls

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4
Q

which other group is fungi closest to?

A

animals

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5
Q

how many described species of fungi are there, and how many are estimated

A

100,000

estimated 0.8 to 5.1 million

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6
Q

which continent has fewer fungi than others and why

A

africa

soil acidity

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7
Q

why is there a positive correlation between fungi abundance and annual precipitatoin

A

mycelium cannot prevent water loss

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8
Q

show the diversity of fungal size

A

smallest e.g. yeast - 3-4ym long

armellaria ostoyae - honey fungi worlds largest organism
4 square miles large

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9
Q

describe saprotrophs

A

get energy from already dead material many have fruiting bodies

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10
Q

describe symbionts

A

interact with plant rooting sytem

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11
Q

desccribe how symbionts increase nutrtient uptake

A

release enzymes into the soil that alter the pH

have many specific nutrient transporters

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12
Q

what % of plants dont have mycorrhizae

A

90%

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13
Q

what percentage of crop plants are lost to fugal pathogens , how many people could this feed?

A

8-10%

feed 600 million

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14
Q

why would it be catastrophiv if we had no more saprotrophic fungi?

A

without them we would get an acuumulation of plant remains nutrinets would be bound up and soil depleted of atmospheric CO2 for photosynthesis

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15
Q

describe breifly the growth pattern of fungal growth

A

spore - dormant
hyphae - long branching filamentous structure
mycelium - collective name for mass of hyphae derived from one spore

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16
Q

hyphae can take up ______ quickly but lose ______ quickly

A

nutrients

water

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17
Q

_________ fungi form hyphae

A

filamentous

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18
Q

what is different about oomycetes and fungi

A

oomyects have cellulose as well as chitin

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19
Q

describe the layers of the fungal cell wall

A

inner most layer - chitin and proteins

protein layer

reticulum - proteins and glucans

outer layer glucans

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20
Q

functions of the fungal cell wall

A 
maintain cell shape 
barrier to the external world 
molecular sieve 
cellular protection 
antigenic properties
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21
Q

fungal hyphae always grow from the ____. here the cytoplasm is _____ and their are more ________

A

Tip
denser
mitochondria

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22
Q

where does digestion occur in fungi

A

hyphal tips

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23
Q

fungi are heterotrophic what does this mean

A

acquire external sources of food

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24
Q

fungi excrete enzymes to perform __________ digestion.

A

extracellular digestion

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25
Q

describe the process of extra cellular digestion

A

vesicles fuse with plasma membrane and release digestive enzymes and cell compents

digestive enzymes bream down extra cellular proteins a d small organic molecules

organic molecules are taken into hyphal via plasma membrane transporter proteins

higher solute concentration in hypha causes water uptake via osmosis

as a result cells enlarge and hyphal tip extends new cell wall materials are added to cell wall

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26
Q

desscribe the following zones of fungi

  • extension
  • productive
  • fruiting
  • aged
A

extension - digestion and excretion

productive zone - fungal colonny produces reproductive structures

fruiting zone = initation of fruting zone

aged zone = hyphae become vaculated and empty - autolysis occurs

27
Q

define homothalic

A

mate with themselves

28
Q

define heterothalic

A

heterothalic only isolates of oppsoite mating type can mate

29
Q

why did anisogamy species used to be named twice?

A

male and female parts look different

30
Q

four larger groups of fungi

A

higher fungi - ascomycota and basidiomycota - have sperate hyphae

zygomycota - non seperate hyphae one long cell with several nuclei

imperfect fungi - no sexual stage known

31
Q

describe basidiomycota, how many species?

A

club fungi
fruiting body = mushroom
31,500 described species

32
Q

fungi can get so large because their growth is _______

A

indeterminate

33
Q

describe the basidium

A

microscopic spore producing structure - basidia presence is charcteristic of basidomycota

forms basdidia from which spores form

34
Q

describe the reproduction of basiodomycota, stating wether diploid dikaryotric or haploid at each stage

A

1) spores land and germinate - haploid
2) hyphal union - hyphale fuse and plasmogamy occurs - dikaryotic
3) fruiting body forms - develops above ground gills lined with hymenium still dikaryotic
4) karyogamy - fusion of haploid nuclei in the basidium becomes diploid - 2n
5) meiosis occurs to form basidiospores - released and are haploid

35
Q

are spores toxic?

A

no, its metabolites within the mushroom that are toxic

36
Q

what is the largest phyla of fungi and how many are there

A

ascomycota

64,000 species

37
Q

define the ascus

A

microscopic sac like sexual structure where the spores are formed

38
Q

desribe the life cycle of a ascomycota

A

1) formation of gametangia = sexual structures formed from thin hyphae = trichogyne - ascogonium and antheridium
2) nuclei migrate towards the ascogonium, forms a dikaryotic mycelium from which an ascocarp forms (fruiting body)
3) hymenium forms from ascocarp, tissue layer where the cell develop into asci in the bottom of the cup
4) karyogamy occurs - fusion of two haploid nuclei in the ascus followed by meiosis and mitosis

39
Q

describe zygomycota

A

molds symbionts and pathogens

small phylum 1050 described species

40
Q

describe the sex of zygomycota

A

hyphae of oppsoite mating types grow side by side

tips develop into gametangia which produce gametes

gametangia and gametes fuse

resulting zygote develops into a resistant zygospore via plasogamy

all haploid up till this point

fertilises itself - karyogamy into a diploid multinucleate zygospore with zygosporangium

41
Q

define plasmogamy and karyogamy

A

plasmogamy = fusion of two hyphae

karyogamy = fertilisation

42
Q

why does wood pose a porblem to fungi and how do they overcome it? what is the brown rot fungi method

A

OH groups in lignin causes tight bonds to cellulose and hemicellulose

forming a barrier to enzymes and prevents penetration of lignocellulytic enzymes into the interior structure

fungi have special ligninases that can break it down but it takes ages

brown rot fungi - breaks down the cellulose by using hydrogen peroxide produced from hemicellulose - diffuses into the tissue leading to decay and cracks into cuboids

43
Q

describe how pathogenic fungi decay trees

A

access the centre of the tree via the xylem of phloem

dead material in the centre is degraded and pathogen moves outwards

44
Q

lichens are a mutualistic symbiotic relationoship between what?

A

fungus and an algae/cyanobacteria

45
Q

describe the relationship between fungi and alage in lichen

A

alage provides food for the fungi and the fungi provides water and protects the alage from the environment

46
Q

what are the two types of mycorrhizae

A

endo - hyphae penetrate the cells

ecto - hyphae dont penetrate the cells

47
Q

3 types of endomycorrhiza

A

arbuscular - form structures within cells
ericoid
orchidaceous mycorrhiza

48
Q

the two ways of infection by fungi

A

necrotrophic

biotrophic

49
Q

how do necrotrophs work?

A

destroy host tissue via hydrolytic enzymes then feed on the dead plant material

50
Q

how do biotrophs work

A

invade tissue without killing it and rely on the living tissue

51
Q

what triggers a hemibiotroph to become a necrotroph

A

penetrating the tissue

52
Q

what is the infecting structure of airborne biotrophs called

A

appressorium

53
Q

what is the response of plants to destroy an invading biotroph

A

kill their own cells

54
Q

what is the haustorium?

A

a specilaised hyphae used to extract nutrtients from living cells in biotrophs

55
Q

why are biotrophs a large problem to argiculture

A

reduces yield as photosynthesis reduces

pathogen reduces defence and hence suseptibility to other diseases

56
Q

what type of fungus causes the following diseases

A

stem rust - basidiomycete

powdery mildew - ascomycete

57
Q

cost of necrotrophs to agriculture in USA through the 1990s

A

3 billion

58
Q

describe mycotoxin deoxynivalenol aka vomitoxin

A

virulence factor
problem in devleoping countries
binds to ribosomes causing cell deaths

59
Q

dutch elm disease was caused by _______ spread by _____

A

ascomycete fungus spread by elm bark bettle

60
Q

describe biocontrol techniues to deal with fungal pathogens

A

hyperparasitic fungi grow on the bad fungi

61
Q

what is intersting about the cordyceps phyla

A

type of ascomycetes that are involved in causing insects to become zombie like

62
Q

describe the nematophagus fungus

A

eats nematodes

inflatable loops and snares

63
Q

what is chytridomycosis? describe its unique reproduction strategy when a japanese tree frog is its host

A

disease caused by chytrid fungus that infects amphibians worldwide

invades skin and f=grows infected skin cant osmoregulate

makes japanese tree frogs make longer calls which attracts more females increasing the chance of the pathogen spreading

Semester 2 Exams (10 decks)

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