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Chapter 30 Fungi - FUNGI...

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FUNGI --fungi can be decomposers, parasites, or mutualists (benefits the host also: fungi gives nitrogen and phosphorus in  exchange for photosynthetic products/sugars) I. Why do biologists study fungi? a. Fungi feed land plants i. Mycorrhizal -fungi that live in close association to plant roots Without these fungi, plants grow much slower b. Fungi speed the Carbon Cycle on land i. Historical evidence: 1. Lack of fungi: Carboniferous period has few saprophytes —fungi that live by digesting dead plants—and coal was formed because of the buildup of dead plants. Fungi were absent because the present coal-forming-swamps were too acidic. 2. Abundance of fungi: The end of the Permian period had a mass extinction. During that time, fungi numbers spiked because there was so much dead matter/food for them. ii. Carbon cycle: 1. Fixation of carbon by land plants—carbon in atmospheric CO 2 is converted to cellulose, lignin, etc and stored in plants. 2. Fungi digest lignin and cellulose so the carbon can be recycled into glucose and CO 2 to feed others so they can perform cell respiration. (They make the cycle turn rapidly if fungi were absent, carbon would be trapped in plants and the cycle would be slow). 3. Release of CO 2 from plants, animals, fungi due to cellular respiration—the oxidation of glucose and ATP production. (Figure 30.3) c. Fungi’s economic impacts i. Fungi are generally more helpful than harmful and affect many species ii. Humans 1. Harmful: Parasitic fungi in humans—athlete’s foot, ringworm, etc. But, only a few fungi species make humans sick, compared to bacteria. 2. Helpful: Antibiotics for bacterial infection iii. Crops/Food 1. Harmful: infects crops a. Wheat, corn, barley, and other grain crops infected by fungi called rusts, smuts, mildews b. Saprophytic fungi spoil crops, esp. fruit and veggies. 2. Helpful: Fungi needed to make bread, soy sauce, cheese, beer, etc. and fungal enzymes used to make some foods better. iv. Trees 1. Chestnut and elm species important from elsewhere had fungi species on it. These fungi infected local elm and chestnut that had no resistance to it, so they all died. II. How do biologists study fungi?—morphology, phylogeny a. Millions of fungal species. Many are undiscovered b. Morphological traits i. Fungi only have 2 growth forms: 1. Yeasts —single-celled a. small and easy to manipulate, so used in labs a model organisms 2. mycelia —multicellular, filamentous structures a. most fungi are this type, so used for morphological studies ii. Fungal mycelium traits 1. Can grow really big if it has nutrients. It is one of the oldest and biggest living things.
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2. Dynamic nature—grows in the direction of food and dies in areas where food is scarce. Body shape can change. 3. Hyphae —individual structures that make up the mycelium a.
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