Fungal Ecology

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Author:
Miskozi
ID:
24196
Filename:
Fungal Ecology
Updated:
2010-06-19 20:26:25
Tags:
fungi fungus ecology mycology
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Description:
Questions covering material from Lecture 18: Fungal Ecology in third year mycology course at UWO.
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  1. What is the weight in leaves formed by a single tree over a 10-year period?
    2 tons
  2. What is the weight of leaves and branches dropped annually in an acre of hardwood forest? Any different in a tropical rainforest?
    • 1 to 2 tons in a hardwood forest
    • 60 tons in a tropical rainforest
  3. What are the four large ecological impacts fungi had when they first evolved onto land with plants?
    • Degradation and decomposition of organic material
    • Mycorrhizae (helping many plants obtain phosphorus)
    • Lichens (initial colonization of rocks and first soils)
    • Food (source of food for animals)
  4. What are major negative ecological impacts of fungi?
    Fungi are parasites and pathogens to many plants. In particular, Chestnut Blight and Dutch Elm Disease has radically altered the composition of upland and floodplains forests. Some animals are at risk too, as amphibians are in major decline due to fungal parasites.
  5. How do fungi aid in the dissolution of rock to make soil?
    Fungi use extracellular digestion to break down nutrients for absorption. They secrete enzymes in order to do so. Some enzymes, such as Oxalic acid, have the added effect of breaking down calcareous bedrock as well.
  6. What are the steps of cellulose decomposition?
    • Cellulase breaks down cellulose into long B 1,4 anhydroglucose chains.
    • Cellulase then takes a second whack at it by taking those chains and breaking them down into cellobiose.
    • Cellobiose is then broken down into glucose by cellobiase, and then finally the glucose is absorbed into the mycelium.
  7. What are the numbers of microorganisms in the soil?
    • True bacteria 10^6 to 10^9
    • Actinomycetes 10^5 to 10^6
    • Protozoa 10^4 to 10^5
    • Algae 10^1 to 10^3
    • Fungi 10^4 to 10^5
  8. What is the only other microorganism(s) more commonly found in a gram of soil than fungus?
    True bacteria and actinomycetes
  9. What is find in equal amounts with fungi in 1 gram of soil?
    Fungi and protozoa are found in equal amounts
  10. What is found more frequently in a gram of soil, fungus or algae?
    Fungus
  11. What are the three fungal life strategies?
    • R-selected
    • S-selected
    • C-selected
  12. In one sentence, what defines r-selected fungi?
    Rapid rates of reproduction with short life-spans.
  13. In one sentence, what defines s-selected fungi?
    Survival in stressful environments.
  14. In one sentence, what defines c-selected fungi?
    Competitive selection, combative fungi that use enzymes to defend themselves as well as in other creative ways.
  15. Name three genus examples of r-selected fungi.
    • Muror
    • Rhizopus
    • Philobolus
  16. Where are r-selected fungi most common?
    Soil and dung
  17. What are some characteristic growth patterns of r-selected fungi?
    • Mycelium develop quickly when nutrients are present.
    • Sporangiophores develop quickly.
    • Mycelium collapses soon after nutrients are depleted.
  18. Name an example of S-selected fungi.
    Some Saccharomyces species can tolerate high osmotic stress.
  19. What is an antagonism?
    When one organism is harmed by another.
  20. How do fungi modify the chemical make-up of their environment?
    • Enzymes break down materials into glucose.
    • Excrete metabolic wastes and by-products which may be toxic to the fungus that produced them or to other fungi, or other microorganisms.
    • Fungi increase respiratory CO2 concentration in soil, as well as increase the amount of alcohols and acids and also produce antibiotics.
  21. What is the current estimate for the number of species of fungus worldwide? How was this estimate calculated?
    • 1.5 million species worldwide
    • Based on the observed ratio of fungi to flowering plants where the number of fungi have been sufficiently studied to estimate diversity.
  22. What percentage of the estimated number of fungal species worldwide have actually been described?
    Only 5% of 1.5 million
  23. What is the rate of new fungal species identification?
    1000 to 1200 new species of fungi per year are discovered
  24. How many years will it take to describe 1 million species?
    1000 years
  25. What percentage of higher plant species are associated with mycorrhizae?
    90%

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