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BESC 204 Exam 3 Review Que4stions and Answers
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BESC 204 Exam 3 Review Que4stions and Answers
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BESC 204 Exam 3 Review Que4stionsand Answers
Explain the primary ecological role of fungi. - Answer --Most fungi are saphrobes,
meaning they absorb nutrients from non-living organic materials
-Their primary role is breaking down material
List the structural components of plants that fungi can degrade. - Answer --Starch and
other carbs are broken down by amylase
-Cellulose is broken down by cellulase
-Hemicellulose is broken down by hemicellulase
-Cutin is broken down by cutinase
-Pectin is broken down by pectinase
-Lignin is broken down by ligninase
-Zygomycetes break down simple sugars
-Ascomycetes break down more complex molecules like cellulose
-Basidiomycetes break down much much more complex things like lignin
Explain the concept of nutritional succession. - Answer --Chytrids
-Some live in stomachs of cows to help break down cellulose
-They are anaerobic
-They don't have mitochondria, they have their own special organelles
Define R-selected and K-selected. - Answer --Most common when talking about
reproduction
-N = Number/population
-R = Growth/reproduction
-K = Carrying capacity (limit)
-As the number of individuals grows, the reproduction rates (R) will also grow until they
reach their limit, or, carrying capacity (K)
-Zygomycetes will favor R-selected
-Basidiomycetes will favor K-selected
Explain the method of spore discharge utilized by basidiomycetes. - Answer --Spores
have weird shapes so that they're able to disperse, survive, and attach to a surface
, -Spore dispersal is a 2-step process
-Discharge or release the spores
-Disperse away from the parent
-The Basidium produces basidiospores and shoots them out by using the Buller's Drop
-They need to be launched into the turbulent layer (about 5 inches off the ground) so
that the wind can carry them
-If they're in the lamellar layer (close to the ground), the wind won't be able to carry
them
How does the term Buller's Drop relate to spore discharge? - Answer --Basidiospores
will secrete sugars
-It is very humid around the gills, so a water droplet will begin to form
-The droplet will continue to get bigger and bigger until it reaches a point where it comes
into contact with the basidiospore and collapses
-When it collapses, the basidiospore launches off the gills of the basidium
-There's a lot of momentum behind this process
-Note, Mushrooms cool themselves, and they do this because if it gets too hot, the
Buller's Drop will evaporate
Detail (with examples) spore dispersal mechanisms utilized by fungi. - Answer --
Coprinus Ink Cap:
-Secretes chitinases that break down the tip of the mushroom
-They do this because they shoot their spores into the middle, and by breaking down
the tip, the bottom is always the most mature basidium
-Colletotrichum:
-Make Servuli, which are basically microscopic mushrooms
-The Conidia have an adhesive on only one side of the spore, this way when they fall,
they have a 50/50 chance of attaching
-This allows them to attach to the whole plant, not just where the water droplet falls
-Birds Nest Fungus:
-Make cup-like structures that have packets of spores
-As a water droplet falls into the cups, it shoots the spores out
-Spiral Spore Shape:
-Some make a spiral shape that leaves room for air in the center
-This allows them to float on water so they can eventually attach to something
-Hook Spore Shape:
-Some fungi, like river that infect the roots of different trees and plants in the river, have
a curved, hook-like shape
-This allows them to hook onto and attach to whatever substrate, like roots, that it lands
on after being shot out/dispersed
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