Chapter 37 n Plant Nutrition Nutrients n Essential: not made by the plant but required for the plant life cycle n Macro- (large amounts) carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, potassium, calcium, magnesium n Micro- (small amounts; cofactors of enzyme action) chlorine, iron, boron, manganese, zinc, copper, molybdenum, nickel n Deficiency chlorosis (lack of magnesium; chlorophyll production) chlorosis Soil n Determines plant growth & variety (also climate) n Composition/horizons: n topsoil (rock particles, living organisms, humus = partially decayed organic material) n loams (equal amounts of sand, silt, and clay) Nitrogen Fixation n Atmosphere = 80% N 2 not available to animals or plants directly. Requires bacteria! n Conversion to: ammonium (NH 4 +) or nitrate (NO 3 -) n Bacteria types: Ammonifying (humus decomposition); nitrogen-fixing (atmospheric N 2 ); nitrifying (convert NH 4 + to NO 3 -); denitrifying (convert NO 3 - to N 2 ) n Nitrogen fixation; crop rotation (cotton soybeans) Plant symbiosis, I n Rhizobium bacteria (found in root nodules in the legume family) n Mutualistic: legume receives fixed N 2 ; bacteria receives carbohydrates & organic materials Plant symbiosis, II n Mycorrhizae (fungi); modify plants roots n Mutualistic: fungus receives sugar; plant receives increased root surface area and increased phosphate uptake n Two types: ectomycorrhizae u ensheaths the roots n endomycorrhizae u (90% of plants) through cell wall but not cell membrane Plant parasitism & predation n Mistletoe (parasite) n Epiphytes - plant uses another plant for support, common in rainforests (commensalism) n Carnivorous plants uom/watch?v=MhcOY gCJK4o&feature=rela tedom/watch?v=MhcOY gCJK4o&feature=rela tedom/watch?v=MhcOY gCJK4o&feature=rela ted