Chapter 30 2.20.08

Chapter 30 2.20.08 - Chapter 30 1 Honors Biology Book Notes...

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Chapter 30 1 Honors Biology Book Notes Chapter 30 – Evolutionary Process 2/20/08 - Fungi o Absorb nutrients from other dead/living organisms o Fungi that specialize in absorbing nutrients from living organisms without providing benefit in return are parasitic o Mutualists : organisms that live in association with others and benefit each other o Fungi feed land plants Mycorrhizal : relationship established by plant roots and fungi, benefit both o Fungi speed carbon cycle on land Saprophytes: fungi that make their living by digesting dead plant material During Carboniferous period, environments were too acidic for fungi to grow so dead plant material piled up and because compressed peat Carbon cycle (1) Fixation of carbon by land plants, where CO2 in atmosphere converted to cellulose, lignin, other complex organic compounds in bodies of plants (2) Release of CO2 from plants, animals, fungi as result of cellular respiration Fungi serve to connect 2 steps – they digest carbon-filled parts of dead plants and set them back into cycle o Economic impacts Incidence of fungal infection is low in humans, and many soil- dwelling fungi have produced useful antibiotics o More abundant in species than land plants o Fungal Morphology 2 growth forms (1) Yeasts : single-celled forms (2) Mycelia : multicellular filamentous form Some grow both forms Nature of Mycelium Constantly grow in direction of food sources and die back in areas where food is running out Hyphae : individual filaments making up mycelium, most are haploid or heterokaryotic Heterokaryotic : each cell contains two haploid nuclei, one from each parent
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Chapter 30 2 Septa: crosswalls that break up filaments of hyphae into cell-like compartments Pores : holes in septa which allow nutrients, organelles, nuclei to flow between compartments Coenocytic : lacking septa and therefore having cytoplasm and many nuclei continuous throughout mycelium Since nutrients, mitochondria, genes can flow throughout mycelium, it is considered intermediate between multicellular land plant/animal/huge single-celled organism Fungi have mycelium of huge surface areas to absorb most efficiently, but also dry out easily because of this Mycelium are adaptation to absorptive lifestyle of fungi o 4 Major Categories of Fungi based on sexual reproductive structures
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Chapter 30 2.20.08 - Chapter 30 1 Honors Biology Book Notes...

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