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Biology
Biology
Photo Credit: ©D. Cavagnaro/DRK Photo
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21-3 Ecology of Fungi
Photo credits: ©D. Cavagnaro/DRK Photo
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21-3 Ecology of Fungi
The oldest known fungi fossils are about 230 million years old.
Fungi may have helped early plants obtain nutrients and may have been essential to plants’ colonization of the land.
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4. All Fungi Are Heterotrophs
Fungi rely on other organisms for energy.
Many fungi are saprobes, which are organisms that obtain food from decaying organic matter.
Other fungi are parasites, which harm other organisms while living directly on or within them.
Other fungi are symbionts that live in close and mutually beneficial association with other species.
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Fungi as Decomposers
Fungi as Decomposers
What is the main role of fungi in natural ecosystems?
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Fungi as Decomposers
Fungi maintain equilibrium in nearly every ecosystem, where they recycle nutrients by breaking down the bodies and wastes of other organisms.
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Fungi as Parasites
Fungi as Parasites
What problems do parasitic fungi cause?
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Fungi as Parasites
Parasitic fungi cause serious plant and animal diseases. A few fungi cause diseases in humans.
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Fungi as Parasites
Plant Diseases
Fungal diseases are responsible for the loss of approximately 15% of the crops grown in temperate regions of the world.
In tropical areas, where high humidity favors fungal growth, the loss of crops is sometimes as high as 50%.
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Fungi as Parasites
Examples of plant diseases caused by fungi include:
Corn smut
Wheat rust
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Fungi as Parasites
Human Diseases
Examples of fungus-caused disorders include:
Athlete’s foot
Ringworm
Thrush
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12. Symbiotic Relationships
What kinds of symbiotic relationships do fungi form with other organisms?
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13. Symbiotic Relationships
Mutualists (symbionts)
Some fungi form symbiotic relationships in which both partners benefit.
Two such mutualistic associations are essential to many ecosystems:
lichens
- mycorrhizae
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14. Symbiotic Relationships
Lichens 
Lichens are symbiotic associations between a fungus and a photosynthetic organism.
The photosynthetic organism is either a green alga or a cyanobacterium, or both.
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15. Symbiotic Relationships
Structure of a Lichen
Lichens are a mutualistic relationship between a fungus and an alga or a cyanobacterium, or both. The protective upper surface of a lichen is composed of fungal hyphae. Below this is the layer of cyanobacteria or algae with loosely woven hyphae. The third layer consists of loosely packed hyphae. The bottom layer is a protective surface covered by small projections that attach the lichen to a rock or tree.
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16. Symbiotic Relationships
The algae or cyanobacteria carry out photosynthesis, providing the fungus with a source of energy.
The fungus provides the algae or bacteria with water and minerals and protects the green cells from intense sunlight.
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17. Symbiotic Relationships
Mycorrhizae  
Fungi also form mutualistic relationships with plants. The associations of plant roots and fungi are called mycorrhizae.
Mycorrhizae is essential for the growth of many plants.
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18. Many Fungi are useful to humans
Yeasts – baking and brewing
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19. Many Fungi are useful to humans
Antibiotics – penicillin and cephlosprorin
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20. Many Fungi are useful to humans
Many organic acids are produced with the help of fungi
ex. critic acid in Coke is made with a fungus.
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21. Many Fungi are useful to humans
Stinky cheeses
ex.
blue cheese
camembert
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21-3
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21-3
Which of the following is NOT true of fungi?
Some of them perform valuable service as decomposers.
Some of them have a beneficial association with plants.
Some of them can make their own food.
Some of them cause serious diseases of plants, animals, and humans.
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21-3
Ringworm is caused by a
worm.
fungus.
plant.
protist.
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21-3
Research on mycorrhizae shows that plants
are not dependent on other organisms.
are closely related to fungi.
may depend on other organisms.
are seriously damaged by fungi.
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21-3
In a mutualistic relationship
both partners benefit.
one partner benefits.
neither partner benefits.
neither partners is affected by the other.
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21-3
Lichens are symbiotic associations that might be formed between
a fungus and an animal.
a plant and a bacterium.
a cyanobacterium and a plant.
a fungus and an alga.
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28. END OF SECTION