Topic 12 - Fungi

Question 1

Key features of Fungi?

Answer 1

Body is composed of thin filaments (hyphae)
Hyphae form an interwoven mat (mycelium)
Hyphae are formed of single, elongated cells or multiple cells connected by septa
Cells are bound by cell walls (composed of chitin)

Question 2

What periodically sprouts above the mycelium?

Answer 2

reproductive structures

Question 3

What kind of feeders are Fungi?

Answer 3

heterotrophic

Question 4

List sources where Fungi obtain nutrients

Answer 4

• dead organisms
• parasitism on living organisms
• symbiotic relationships with food providers
• predation

Question 5

How do Fungi digest food?

Answer 5

Digested extracellularly by secreting enzymes; nutrients are resorbed by hyphae

Question 6

Explain fungal propagation

Answer 6

Propagation is via spores
-tiny propagules germinate to produce next generation=>are extremely light (carried in wind)=>often produced in lrg numbers

Question 7

2 kinds of fungal repro?

Answer 7

Asexual

Sexual

Question 8

Fungal cells and spores are..?

Answer 8

haploid

Question 9

Explain asexual repro in fungi?

Answer 9

Occurs in stable environments
fruiting bodies grow above mycelium & release haploid spores (produced via mitosis)
results in rapid repro of genetically IDENTICAL individuals

Question 10

Explain sexual repro in fungi?

Answer 10

Occurs when enviro conditions deteriorate
hyphae of 2 compatible mating types fuse
nuclei fuse=>form zygote
Zygote undergoes meiosis=>forming haploid sexual spores
Spores are released=>germinate
Resulting offspring are genetically DISTINCT from parent cells

Question 11

Major fungal groups (taxa) are?

Answer 11

Chytrids
Zygomycetes
Glomeromycetes
Ascomycetes
Basidiomycetes

Question 12

A bit about Chytrids?

Answer 12

Live in water (unique!)
Spores swim via flagella
Feed mainly on dead aquatic plants
Some are parasitic

Question 13

A bit about Zygomycetes?

Answer 13

Typically live in soil
feed on decaying organic matter
Asex. repro is common, but sex. repro does occur
Example: bread mould

Question 14

A bit about Glomeromycetes?

Answer 14

Grow in intimate association of plant roots (actually penetrate root cells)
This association is symbiotic (mycorrhiza)
Important in plant nutrition
Repro. mechanism is unkown

Question 15

A bit about Basidiomycetes? *

Answer 15

Known as “club fungi” =>produce club shaped repro. structures
Reproduction is sexual
Incl. most of edible mushrooms

Question 16

A bit about Ascomycetes? *

Answer 16

Known as “sac fungi” => spores contained in a sac
Repro. is sexual or asexual
Diversity of forms: wood decay fungi, moulds on fruit n veg (penicillium), yeasts (unicellular)

Question 17

Basidiomycetes life cycle?

Ascomycetes life cycle see diagram in lectures (need to know)

Answer 17

Sexual repro when 2 hyphae fuse=>fused hyphae grow into mycelium containing a haploid nucleus from each parent=>Hyphae from mycelium form mushroom=>repro. cells called basidia form on mushy gills=>2 haploid nuclei in each basidium fuse to form a diploid nucleus=>dip. nucleus divides by meiosis=>gives rise to haploid basidiospores=>these are ejected & germinate

Question 18

Major types of mutualistic interactions b/w fungi & other eukaryotic organisms?

Answer 18

Lichens- fungus provides support & protection, also provides food (photosynthate)

Mycorrhizae- intimate assoc. of fungus & plant root, fungus gets photosynthate from plant, plant gets more efficient water extraction from soil

Endophytes- grow w/in above ground plants, can be parasitic or produce beneficial chemicals that deter herbivores

Question 19

Explain fungi’s role as decomposer

Answer 19

Only fungi can digest both lignin & cellulose

Liberate nutrients tied up in dead organisms

Question 20

Agricultural importance?

Answer 20

Plant pathogens (smuts, rusts)
Storage fungi (penicillium)
Landscape pests (kill plants)
Beneficial fungi (parasite/disease to arthropods)

Question 21

Negative role of fungi in human health?

Answer 21

Diseases of skin (ringworm, athlete’s foot)
Vaginal infections (yeast infection)
Disease of lungs

Question 22

Positive role of fungi in human health?

Answer 22

Antibiotics (penicillin, cephalosporin, cyclosporin)
Food (soy sauce, cheese, mushy itself)
Beverage production (alcohol)
Bread production (yeasts)