BIOL 2061 1st Edition Lecture 13Outline of Last Lecture I. Plant growth and developmentII. Distinctive architectureIII. Maintenance of Stem cellsIV. Primary meristemsV. Expansions of cells by waterVI. Modular structureVII. StemsVIII. LeavesIX. Roots Outline of Current Lecture (Chapter 29)I. Plant nutrientsII. Water III. LightIV. Carbon dioxideV. SoilVI. NitrogenCurrent LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.I. Plant Nutrients-a. What does a plant need to grow?i. Sunlightii. Soiliii. Wateriv. Phosphorusv. Magnesiumvi. Ammoniavii. Potassiumviii. Carbon dioxideix. Oxygenx. Calciumb. Macronutrients- are needed and available in large quantities.i. Carbon, oxygen, hydrogen, nitrogen, potassium, calcium, magnesium, phosphorus and sulfur.c. Micronutrients- the plant does NOT need a lot.i. Chlorine, iron, manganese, boron, zinc, sodium, copper, molybdenum andnickel.d. When plants lack nutrients they display deficiency symptomsi. Failure to reproduceii. Tissue deathiii. Chlorosis- yellowing leavesII. Water-a. 90% of the plant by weightb. Some plants have adapted to arid conditions- but all require waterc. Water supplies most of the hydrogen incorporated into organic compoundsd. Water is the solvent for other mineral nutrientse. Water is main transport mediumf. Evaporative loss of water helps to cool plantsg. Water in cells help support pants by maintaining hydrostatic pressureIII. Light-a. All photosynthetic plants require lightb. An essential resourcec. Needed to form covalent bonds during photosynthesisd. Source of energy for plantse. Source of energy in the food webf. Light deprived plants show deficiency symptomsg. Light levels are highly variablei. Mountain tops, canopy top or canopy bottomIV. Carbon Dioxide-a. ** Most of plant dry mass** originates fromCO2 absorbed from the atmosphereb. Photosynthesis rates increase with CO2 concentration until the Calvin cycle enzyme “rubisco” has become fully saturated withCO2.c. Carbon Dioxide Limitation-i. Plants need CO2 to generate their own food via photosynthesisii. Plants grown in CO2 enriched air will increase with growth until another nutrient becomes limitingiii. Hot, and dry conditions make plant vulnerable to low levels of CO2 because the stomata are closed off to conserve water1. Closed stomata limit photosynthesis because the plants can’t absorbCO2.iv. Many plants have adapted to absorb CO2 while preserving water.V. Soil-a. Plants obtain nutrients from soilsb. Plants contribute to soils as they decomposec. Soils are shaped by climate, organisms, parents material, relief and timed. Organic soil constituents-i. Humus- organic constituents of soil1. Largely derived from plant detritus, animal waste and decaying animal bodiesii. Humus poor soils- have less than 1% of organic materialiii. Humus rich soils- have greater than 8% organic materialiv. Optimal growth requires near 8% because humus helps soils hold more water and ions.e. Inorganic soil-i. Derived from physical and chemical breakdown of rock from weatheringii. Leaching is the dissolution and removal of inorganic ions as water percolates thoughiii. Soils are classified by the amount of course and fine materials as sand, silt, clay and loamiv. Porous (sandy) soils allow air and water movementv. Sandy soils are well-aerated, water flows quickly reducing availability to roots and leaching out mineralsvi. Silt and clay soils lose less water because they fit tightly together1. More ionic nutrients are retained, and sometimes too wellf. Soil fertilizers-i. Can compensate for deficiencies in soils ormineral content to improve soilfertilityii. Organic Fertilizer- most minerals are bound to organic molecules and released slowly (manure and compost)iii. Inorganic Fertilizer- inorganic molecules are immediately useful but can be leached awayVI. Nitrogen-a. Large amounts are needed for synthesis of amino acids, nucleotides, alkaloids and othersb. Plants can’t use nitrogen gas but can use it in forms or ammonia, ammonium or nitratec. Nitrogen Fixation-i. Conversion on nitrogen gas into plant available forms of nitrogenii. Industrial fixation 1. happens in factories, 2. reduction of N2 to NH3 3. high energy requirements make