BIOL 240W 1st Edition Lecture 2 Outline of Last Lecture I. Overview of Syllabusa. General Informationb. Exam formatc. How to be successful in BIOL 240WII. Introduction to Soil and Plant Nutritiona. Where do plants get their nutrients from?Outline of Current Lecture I. Essential ElementsII. MacronutrientsIII. MicronutrientsIV. Nutrient DeficienciesV. Soil PropertiesCurrent LectureI. Essential Element- a chemical element that is required for a plant to complete its life cycle and produce another generationa. Researchers determine essential elements by using a hydroponic cultureb. Hydroponic cultures grow plants in mineral solutions instead of soil. There are 17essential elements needed by plants (found in table 37.1 of text).II. Macronutrientsa. Nine of the essential elements are macronutrientsb. They are called macronutrients because plants require them in large amountsc. The big three micronutrients are Nitrogen, Phosphorous, and Potassiumi. Nitrogen is the biggest limiting factor in the growth of plants (not readily available in large amounts). It is a component of nucleic acids, protein, chlorophyll, etc. Nitrogen is scavenged from soil as NO3- or NH4+.ii. Phosphorous is a component of nucleic acids, phospholipids, ATP, etc. It isscavenged from soil in the form of PO42-.iii. Potassium is scavenged in the soil as K+ (potassium ion). It is a cofactor forprotein synthesis, and an osmoregulator to determine the flow of water in and out of plant cells.III. MicronutrientsThese 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.a. The other eight essential elements are only needed in small amounts. These are the micronutrients.b. Rarely limiting to the plant growth.c. Examples include chlorine, iron, manganese, etc.d. Function as co-factors, or nonprotein “helpers” in enzymatic reaction. i. Ex:Iron in the heme compound is critical for electron transport in photosynthesis and respiration (cytochromes)IV. Nutrient Deficienciesa. Most deficiencies involve nitrogen, potassium, and phosphorous.b. Micronutrient shortages are less common. They are normally due to soil composition, and only a small amount of mineral is needed to correct a deficiency.c. Symptoms can be based on mineral’s function as a nutrient (ex: deficiency in magnesium, a component of chlorophyll, causes yellowing of leaves). Other deficiencies can be determined based on the leaves of the plant.d. Symptoms also depend on the mineral’s mobility in the plant.i. Highly mobile nutrients are seen first in older tissues. Young, growing tissues preferentially accept nutrients over older tissues(ex: Mg).ii. Immobile nutrients appear in young tissues because older tissues may have adequate amounts that they retain. iii. Young seedlings do not show mineral deficiency symptoms because minerals released from stored reserves in the seed itself meet their mineral requirements. e. When a mineral is deficient, genes may be turned on or off to compensate (molecular response). In lab, we will be investigating the changes in microRNA gene expression in response to nutritional deficiencies. V. Soil Propertiesa. Nutrients are scavenged from the soil in the form of ions. Its composition and therole of living organisms in the top layer of soil are important.b. Soils are divided into layers called horizonsi. Horizon A (topsoil)- mixture of broken-down rock of various textures, living organisms (decomposers and organisms that mix the soil), decaying organic matter (humus)1. Humus- retains water while still remaining porous, increases capacity for cation exchange, reservoir for mineral nutrients2. Loams- topsoil supporting most abundant growth composed of equal amounts of sand (course particles), silt (medium-sized particles), and clay (small particles). They have ample surface area for adhesion and retention of minerals and water while enabling diffusion of oxygen to roots.3. Sandy soils do not retain enough water to support plant growth, while clay soils retain too much water.ii. Horizon B contains limited organic material and larger mineral fragments.iii. Horizon C is