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02:50 02:50Table 29.1 mentions that chytrids are responsible for massive die-offs currently occurring in amphibians. Review Koch's postulates; then design a study showing how you would use Koch's postulates to test the hypothesis that chytrid infections are responsible for frog deaths.
What does it mean to say that a hypha is dikaryotic?
a. Two nuclei fuse during sexual reproduction to form a zygote.
b. Two independent nuclei, derived from different individuals, are present in each cell.
c. The nucleus is diploid or polyploid — not haploid.
d. It is extremely highly branched, which increases its surface area and thus absorptive capacity.
The Greek root ecto means 'outer.' Why are ectomycorrhizal fungi, or EMF, aptly named?
a. Their hyphae form tree-like branching structures inside plant cell walls.
b. They are mutualistic.
c. Their hyphae form dense mats that envelop roots but do not penetrate the cell walls.
d. They transfer nitrogen from outside their plant hosts to the interior.
Explain why fungi that degrade dead plant materials are important to the global carbon cycle. Do you accept the text's statement that, without these fungi, 'Terrestrial environments would be radically different than they are today, and probably much less productive'? Why or why not?
Lignin and cellulose provide rigidity to the cell walls of plants. But in most fungi, chitin performs this role. Why is it logical that most fungi don't have lignin or cellulose in their cell walls?
Lawns are sometimes fertilized with nitrate that can be washed into neighboring woodlots by rain. If the trees in that woodlot are associated with EMF, what effect might the excess nitrate have on the fungi and/or trees?
a. Fungal growth may be stimulated, causing the trees to transport more nitrogen to the fungi.
b. The fungi may secrete more peptidases to break down the nitrate.
c. The trees may take up the nitrate directly into their roots and rely less on the fungi.
d. The excess nitrate may stimulate the fungi to transport more sugar to the trees.
