4. Fungal Biodiversity

Question 1

Oomycota summary

Answer 1

• coenocytic (non-septate) hypha
• oogonia, antheridia, oospores (sexual reproduction)
• zoosporangia, biflagellate zoospores with two (tinsel and whiplash) flagella (asexual reproduction)
• fungus-like organism (cellulose cell walls, biflagellate spores)
• water molds and pathogens

Question 2

Zygomycota summary

Answer 2

• largely terrestrial fungi (pin moulds)
• coenocytic (non-septate) hyphae
• sexual zygospores and gametangia
• asexual non-motile sporangiophores and sporangia

Question 3

Ascomycota summary

Answer 3

• septate hyphae
• 8 ascospores in an ascus (sexual, meiosis then mitosis)
• genetic markers segregated and expressed during meiosis
• discharged by the rupture of an operculum at the ascus apex, white cloud of spores
• conidium in mitosporic species (asexual)

Question 4

Basidiomycota summary

Answer 4

• include mushrooms and toadstools (class Agaricomycetes)
• two nuclei in each cell of the mycelium (dikaryon)
• septate hyphae with clamp connections
• basidiocarps (fruit bodies) form basidia which form 4 basidiospores

Question 5

oomycetes sexual reproduction

Answer 5

• male antheridia fertilises female oogonia
• oospores develop inside fertilised oogonium
• within or between individuals
• oospores have a thick cell wall
• oospore diameter ~70 micrometers

Question 6

oomycetes asexual reproduction

Answer 6

• sporangia form biflagellate zoospores (one tinsel flagella, one whiplash)
• zoosporangia around 70 micrometers wide and 300 micrometers long
• zoospores around 5-10 micrometers, not to be mistaken under the microscope with ciliate protozoa (move slower, larger in size)

Question 7

zygomycota asexual reproduction

Answer 7

• non-motile sporangiospores from sporangium (held up by melanised hyphae around 25 micrometers diameter with high osmotic pressure, surround columella)
• sporangium 125 micrometers diameter
• can be yellow

Question 8

zygomycota sexual reproduction

Answer 8

• plus and minus fuse into gametangium (~750 micrometers across)
• karogamy and meiosis
• form zygospores on long spikes (~300 micrometers)

Question 9

phototropism and gravitropism in Phycomyces blakesleeanus

Answer 9

• positive phototropism, grows towards light
• grows towards blue light more than red light
• negative gravitropism, grows away from gravitational pull

Question 10

Phycomyces photoreceptors

Answer 10

• blue light photoreceptors
• energy is inversely proportionate to wavelength, so blue light has the most energy
• photoreceptor is flavin adenine dinucleotide
• changes shape when blue light hits it, binding to the LOV domain of MADA initiating gene transcription

Question 11

ascomycota, asci

Answer 11

• ascus is ~400 micrometers long and ~15 micrometers wide, ends are flattened
• spore is ~27 micrometers wide
• can see oil droplets inside ascospore at x40, energy storage
• paraphyses transmit shock waves across asci to create puff of ascospores

Question 12

basidiomycota, basidiospores

Answer 12

• Agaricus bisporus in groups of 2
• shiitake in groups of 4
• not spherical
• ~15 micometers by 5 micrometers