1. Fungi

2. You are presented with several single-celled organisms, including one thought to belong to the kingdom Fungi. What unique feature helps you identify the fungus?
presence of mitochondria
absence of chloroplasts
presence of nuclei
presence of chitinous cell walls
Answer: d 2

3. You are presented with several single-celled organisms, including one thought to belong to the kingdom Fungi. What unique feature helps you identify the fungus?
presence of mitochondria
absence of chloroplasts
presence of nuclei
presence of chitinous cell walls 3

4. Which phylogenetic tree represents the evolutionary history of the fungi based on the most recent data? c) d)
Answer: c 4

5. Which phylogenetic tree represents the evolutionary history of the fungi based on the most recent data? c) d) 5

6. You are given a fungus to identify
You are given a fungus to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of fungus is this?
zygomycete
chytrid
deuteromycete
ascomycete
Answer: d 6

7. You are given a fungus to identify
You are given a fungus to identify. It has a fruiting body that contains many structures with eight haploid spores lined up in a row. What kind of fungus is this?
zygomycete
chytrid
deuteromycete
ascomycete 7

8. Many fungi produce antibiotics, for example, penicillin, that are effective at stopping bacterial growth. Which do you think is the evolutionary advantage to the fungus of secreting antibacterial chemicals?
defense: preventing bacteria from infecting the fungus
defense: preventing bacteria from killing fungal spores
symbiosis: attracting helpful bacteria
competition: destroying bacteria that compete for their food
predation: eventually consuming the bacteria
Answer: d 8

9. Many fungi produce antibiotics, for example, penicillin, that are effective at stopping bacterial growth. Which do you think is the evolutionary advantage to the fungus of secreting antibacterial chemicals?
defense: preventing bacteria from infecting the fungus
defense: preventing bacteria from killing fungal spores
symbiosis: attracting helpful bacteria
competition: destroying bacteria that compete for their food
predation: eventually consuming the bacteria 9

10. Which of the following phyla includes aquatic, flagellated fungi?
Ascomycota
Basidiomycota
Chytridiomycota
Zygomycota
Answer: c 10

11. Which of the following phyla includes aquatic, flagellated fungi?
Ascomycota
Basidiomycota
Chytridiomycota
Zygomycota 11

12. Which of the following statements about mycorrhizae is false?
They are important in natural systems and agriculture.
Almost all vascular plants have them.
Foresters inoculate pine seedlings with them to promote growth.
They colonize soils by dispersing spores that form new mycelia.
They are in a commensalistic relationship with plants.
Answer: e

13. Which of the following statements about mycorrhizae is false?
They are important in natural systems and agriculture.
Almost all vascular plants have them.
Foresters inoculate pine seedlings with them to promote growth.
They colonize soils by dispersing spores that form new mycelia.
They are in a commensalistic relationship with plants.

14. All of the following are lineages of fungi except
a) chytrids.
b) zygomycetes.
c) glomeromycetes.
d) ascomycetes.
e) conidia.
Answer: e

15. All of the following are lineages of fungi except
a) chytrids.
b) zygomycetes.
c) glomeromycetes.
d) ascomycetes.
e) conidia.

16. Lichens are
mutually beneficial relationships between fungi and plant roots.
symbiotic associations between photosynthetic organisms and fungi.
a type of plant pathogen.
a type of marine eukaryote.
single-celled, flagellated protist ancestors of fungi.
Answer: b

17. Lichens are
mutually beneficial relationships between fungi and plant roots.
symbiotic associations between photosynthetic organisms and fungi.
a type of plant pathogen.
a type of marine eukaryote.
single-celled, flagellated protist ancestors of fungi.

18. Chytrids are unique among fungi in that they
have flagellated spores
form mutualistic relationships with amphibians
have led to the decline of sheep and cattle populations
have chitinous cell walls
Answer: a

19. Chytrids are unique among fungi in that they
have flagellated spores
form mutualistic relationships with amphibians
have led to the decline of sheep and cattle populations
have chitinous cell walls

20. The practical uses of fungi include all of the following except
systemic mycoses.
reducing high blood pressure.
stopping maternal bleeding after childbirth.
treating bacterial infections.
fuel production.
Answer: a

21. The practical uses of fungi include all of the following except
systemic mycoses.
reducing high blood pressure.
stopping maternal bleeding after childbirth.
treating bacterial infections.
fuel production.

22. Scientific Skills Exercises
The first genome of a mycorrhizal fungus to be sequenced was that of the basidiomycete Laccaria bicolor. In nature, L. bicolor is a common ectomycorrhizal fungus of trees such as poplar and fir, as well as a free-living soil organism. In forest nurseries, it is used in large-scale inoculation programs to enhance seedling growth. The fungus can easily be grown alone in culture and can establish mycorrhizae with tree roots in the laboratory. Researchers hope that studying the genome of L. bicolor will yield clues to the processes by which it interacts with its mycorrhizal partners--and by extension, to mycorrhizal interactions involving other fungi.
Using the whole-genome shotgun method and bioinformatics, researchers sequenced the genome of L. bicolor and compared it with the genomes of some nonmycorrhizal basidiomycete fungi. By analyzing gene expression using microarrays, the researchers were able to compare gene expression levels for different protein-coding genes and for the same genes in a mycorrhizal mycelium and a free-living mycelium. They could thus identify the genes for fungal proteins that are made specifically in mycorrhizae.

23. Based on the table, which fungal species has the most genes encoding membrane transporters (membrane transport proteins)?
L. bicolor
nonmycorrhizal species 1
nonmycorrhizal species 2
nonmycorrhizal species 3
nonmycorrhizal species 4
Answer: a

24. Based on the table, which fungal species has the most genes encoding membrane transporters (membrane transport proteins)?
L. bicolor
nonmycorrhizal species 1
nonmycorrhizal species 2
nonmycorrhizal species 3
nonmycorrhizal species 4

25. Why might you expect to find many genes for membrane transporters in a mycorrhizal fungus such as L. bicolor?
Mycorrhizal fungi exchange nutrients with the roots of their plant hosts and would be expected to use membrane transporters in this exchange.
The numerous chemical reactions that involve mycorrhizal fungi and their plant hosts are catalyzed by membrane transport proteins that function as enzymes.
Complex chemical communication occurs between mycorrhizal fungi and their plant hosts, and membrane transporters are crucial in this process.
Special junctions form between the cells of plant roots and mycorrhizal fungi, and membrane transporters are an important structural part of these junctions
Answer: a

26. Why might you expect to find many genes for membrane transporters in a mycorrhizal fungus such as L. bicolor?
Mycorrhizal fungi exchange nutrients with the roots of their plant hosts and would be expected to use membrane transporters in this exchange.
The numerous chemical reactions that involve mycorrhizal fungi and their plant hosts are catalyzed by membrane transport proteins that function as enzymes.
Complex chemical communication occurs between mycorrhizal fungi and their plant hosts, and membrane transporters are crucial in this process.
Special junctions form between the cells of plant roots and mycorrhizal fungi, and membrane transporters are an important structural part of these junctions

27. The researchers used the phrase “small secreted proteins” (SSPs) to refer to proteins less than 100 amino acids in length that the fungi secrete; their function is not yet known. What is most striking about the SSP data from the table?
The number of genes for SSPs is much higher for L. bicolor than for the other species tested.
L. bicolor is the only fungus tested that has more genes for SSPs than genes for membrane transporters.
All the species tested have approximately the same number of genes for SSPs.
The number of genes for SSPs is much lower for L. bicolor than for the other species tested.
Answer: a

28. The researchers used the phrase “small secreted proteins” (SSPs) to refer to proteins less than 100 amino acids in length that the fungi secrete; their function is not yet known. What is most striking about the SSP data from the table?
The number of genes for SSPs is much higher for L. bicolor than for the other species tested.
L. bicolor is the only fungus tested that has more genes for SSPs than genes for membrane transporters.
All the species tested have approximately the same number of genes for SSPs.
The number of genes for SSPs is much lower for L. bicolor than for the other species tested.

29. The SSP genes shared a common feature that indicated the encoded proteins were destined for secretion. Genes for secretory proteins have a signal-peptide coding sequence at the leading end. The signal peptide at or near the leading end of the polypeptide targets the protein to the ER. Which of the following is a plausible hypothesis for the roles of SSPs in mycorrhizae.
SSPs are proteins secreted by mycorrhizal fungi.
SSPs in mycorrhizal species allow specific substances from the soil to cross a cell membrane.
The function of SSPs in mycorrhizal species is likely to be the same as in nonmycorrhizal species.
SSPs play important roles in the mycorrhizal interaction.
Answer: d

30. The SSP genes shared a common feature that indicated the encoded proteins were destined for secretion. Genes for secretory proteins have a signal-peptide coding sequence at the leading end. The signal peptide at or near the leading end of the polypeptide targets the protein to the ER. Which of the following is a plausible hypothesis for the roles of SSPs in mycorrhizae.
SSPs are proteins secreted by mycorrhizal fungi.
SSPs in mycorrhizal species allow specific substances from the soil to cross a cell membrane.
The function of SSPs in mycorrhizal species is likely to be the same as in nonmycorrhizal species.
SSPs play important roles in the mycorrhizal interaction.

31. The table in the following slide shows data from gene expression studies for the four L. bicolor genes whose transcription was most increased (“upregulated”) in mycorrhizae. For the gene encoding the first protein listed, what does the number 22,877 indicate?
The amount of RNA transcript of this gene made in Douglas fir mycorrhizae was 22,877 times higher than the amount made in poplar mycorrhizae.
The amount of RNA transcript of this gene made in mycorrhizal parts of the fungus when associated with Douglas fir was 22,877 times higher than the amount made in soil mycelium away from plant roots.
The amount of RNA transcript of this gene made in poplar mycorrhizae was 22,877 times higher than the amount made in Douglas fir mycorrhizae.
The amount of RNA transcript of this gene made in soil mycelium away from plant roots was 22,877 times higher than the amount made in mycorrhizal parts of the fungus associated with Douglas fir.
Answer: b

33. The table in the previous slide shows data from gene expression studies for the four L. bicolor genes whose transcription was most increased (“upregulated”) in mycorrhizae. For the gene encoding the first protein listed, what does the number 22,877 indicate?
The amount of RNA transcript of this gene made in Douglas fir mycorrhizae was 22,877 times higher than the amount made in poplar mycorrhizae.
The amount of RNA transcript of this gene made in mycorrhizal parts of the fungus when associated with Douglas fir was 22,877 times higher than the amount made in soil mycelium away from plant roots.
The amount of RNA transcript of this gene made in poplar mycorrhizae was 22,877 times higher than the amount made in Douglas fir mycorrhizae.
The amount of RNA transcript of this gene made in soil mycelium away from plant roots was 22,877 times higher than the amount made in mycorrhizal parts of the fungus associated with Douglas fir.

34. Do the data in the table support the hypothesis that SSPs play important roles in the mycorrhizal interaction?
Yes, because a majority of SSPs in the L. bicolor genome are upregulated in the ectomycorrhizal mycelium.
No, because two of the most upregulated genes in the ectomycorrhizal mycelium encode an enzyme and an enzyme inhibitor rather than SSPs.
No, because it is impossible to draw a conclusion based on data from only four genes when L. bicolor has a total of 2,191 genes for SSPs.
Yes, because two of the most upregulated genes in the ectomycorrhizal mycelium encode SSPs.
Answer: d

35. Do the data in the table support the hypothesis that SSPs play important roles in the mycorrhizal interaction?
Yes, because a majority of SSPs in the L. bicolor genome are upregulated in the ectomycorrhizal mycelium.
No, because two of the most upregulated genes in the ectomycorrhizal mycelium encode an enzyme and an enzyme inhibitor rather than SSPs.
No, because it is impossible to draw a conclusion based on data from only four genes when L. bicolor has a total of 2,191 genes for SSPs.
Yes, because two of the most upregulated genes in the ectomycorrhizal mycelium encode SSPs.

36. How do the data for poplar tree mycorrhizae compare with those for Douglas fir mycorrhizae?
All four genes are more upregulated in poplar mycorrhizae than in Douglas fir mycorrhizae.
All four genes are more upregulated in Douglas fir mycorrhizae than in poplar mycorrhizae.
Some of the genes that are upregulated in Douglas fir mycorrhizae are downregulated in poplar mycorrhizae and vice versa.
The four genes are all upregulated in the mycorrhizae of both trees, but the relative amounts of upregulation differ.
Answer: d

38. How do the data for poplar tree mycorrhizae compare with those for Douglas fir mycorrhizae?
All four genes are more upregulated in poplar mycorrhizae than in Douglas fir mycorrhizae.
All four genes are more upregulated in Douglas fir mycorrhizae than in poplar mycorrhizae.
Some of the genes that are upregulated in Douglas fir mycorrhizae are downregulated in poplar mycorrhizae and vice versa.
The four genes are all upregulated in the mycorrhizae of both trees, but the relative amounts of upregulation differ.

39. Which of the following is the most plausible hypothesis to explain the differences in gene expression between poplar tree mycorrhizae and Douglas fir mycorrhizae?
Poplars, but not Douglas firs, have turned off the expression of some L. bicolor SSP genes.
Differences in the trees’ environments affect which genes are expressed most.
Poplars need more enzyme inhibitors, but fewer enzymes and SSPs, than Douglas firs.
The two types of trees are associated with different species of mycorrhizal symbionts, which have different patterns of gene expression.
Answer: b

40. Which of the following is the most plausible hypothesis to explain the differences in gene expression between poplar tree mycorrhizae and Douglas fir mycorrhizae?
Poplars, but not Douglas firs, have turned off the expression of some L. bicolor SSP genes.
Differences in the trees’ environments affect which genes are expressed most.
Poplars need more enzyme inhibitors, but fewer enzymes and SSPs, than Douglas firs.
The two types of trees are associated with different species of mycorrhizal symbionts, which have different patterns of gene expression.
Answer: b