2.2 Water IB Biology HL 1 Mrs. Peters Fall 2014

U 1. Water  2 Hydrogen atoms + 1 Oxygen atom covalently bonded (polar)  Makes up 70-95% of living things, covers 75% of Earth  DRAW and LABEL this in your notes, showing polarity Red: oxygenWhite: hydrogen

U1. Hydrogen Bond Formation Hydrogen bonds form between water molecules Weak intermolecular forces Weak intermolecular forces Attraction between the slightly positive H and the slightly negative O of different water molecules. Attraction between the slightly positive H and the slightly negative O of different water molecules. Always represented by a dotted line. Always represented by a dotted line. Draw in your notes! Draw in your notes!

U 2. Properties of Water  Cohesion created by the constant forming and reforming of hydrogen bonds between water molecules created by the constant forming and reforming of hydrogen bonds between water molecules Enables water to move against gravity for transport in plants Enables water to move against gravity for transport in plants Creates surface tension Creates surface tension

U 2. Properties of Water  Surface Tension A measure of how difficult it is to stretch or break the surface of a liquid A measure of how difficult it is to stretch or break the surface of a liquid Created by the cohesive property of water molecules Created by the cohesive property of water molecules Water has a greater surface tension than most other liquids Water has a greater surface tension than most other liquids

U 2. Properties of Water Adhesion: waters ability to adhere to other polar molecules by forming hydrogen bonds Useful in plants: absorption of CO 2 for photosynthesis in leaves glogster.com Landryamps.com

U 2 Thermal Properties of Water  High Specific Heat Capacity Can absorb or give off heat energy without changing temperature very much due to the breaking and forming of hydrogen bonds. Can absorb or give off heat energy without changing temperature very much due to the breaking and forming of hydrogen bonds. The amount of energy required to change the temperature of water is relatively high The amount of energy required to change the temperature of water is relatively high

U 2 Thermal Properties of Water  High Specific Heat Capacity Allows organisms to maintain a constant temperatureAllows organisms to maintain a constant temperature Also acts as a temperature regulator within the body (blood moves warmer blood to cooler parts of the body)Also acts as a temperature regulator within the body (blood moves warmer blood to cooler parts of the body)

U2 & A2. Thermal Properties of Water  High latent heat of Vaporization: transformation from liquid to gas Water absorbs a great deal of heat when it evaporates Water absorbs a great deal of heat when it evaporates Used as a cooling mechanism Used as a cooling mechanism Creates sweat in animals and transpiration in plants Creates sweat in animals and transpiration in plants

U2. Thermal Properties of Water  High Boiling Point Highest temperature reached in liquid state Highest temperature reached in liquid state High due to amount of energy required to break H- bonds. High due to amount of energy required to break H- bonds. Water stays a liquid over a broad range of temperatures (0-100 o C), which is most habitats on Earth Water stays a liquid over a broad range of temperatures (0-100 o C), which is most habitats on Earth Solarviews.com

Background Info: Parts of Solutions  Solution: a liquid mixture of 2 or more substances  Aqueous solution: liquid in which water is the solvent

Background Info: Parts of Solutions  Solvent: dissolving agent of solutions  Solute: substance being dissolved

U2. Solvent Properties of Water  Solvent Water’s polarity helps dissolve ions and other polar substances (like dissolves like) Water’s polarity helps dissolve ions and other polar substances (like dissolves like) Creates an excellent medium for transporting substances around the body Creates an excellent medium for transporting substances around the body

U2. Solvent Properties of Water  Solvent Excellent medium for metabolic reactions to take place Excellent medium for metabolic reactions to take place Cytoplasm: glycolysis, protein synthesis reactionsCytoplasm: glycolysis, protein synthesis reactions Nucleoplasm: DNA replication, transcriptionNucleoplasm: DNA replication, transcription Stroma: light reactions of photosynthesisStroma: light reactions of photosynthesis Blood Plasma: loading and unloading of respiratory gases; clottingBlood Plasma: loading and unloading of respiratory gases; clotting

U2. Solvent Properties of Water  Solvent Examples Plants: vascular tissue carries water and dissolved substances Plants: vascular tissue carries water and dissolved substances Xylem carries water and minerals from roots to leavesXylem carries water and minerals from roots to leaves Phloem carries dissolved sugars from leaves to stems, roots and flowersPhloem carries dissolved sugars from leaves to stems, roots and flowers Diffen.com

U2. Solvent Properties of Water  Solvent Examples Animals: blood is the most common transport medium, largely made up of water (blood plasma) Animals: blood is the most common transport medium, largely made up of water (blood plasma) Transports: red blood cells, white blood cells, platelets, dissolved molecules (glucose, amino acids, salts, urea)Transports: red blood cells, white blood cells, platelets, dissolved molecules (glucose, amino acids, salts, urea)

U2.Common Aqueous Solutions Aqueous SolutionLocationCommon Reaction CytoplasmFluid inside cells but outside organelles Glycolysis Protein synthesis NucleoplasmFluid inside nuclear membranes DNA replication Transcription StromaFluid inside chloroplast membranes Light independent reactions of photosynthesis Blood PlasmaFluid in arteries, veins, and capillaries Loading and unloading of respiratory gases Blood clotting

U3. Substances can be hydrophilic  Hydrophilic:  “Water loving”  any substance with an attraction to water Substance does not have to dissolve Substance does not have to dissolve EX: glucose, sodium and chlorine ions, other polar substances EX: glucose, sodium and chlorine ions, other polar substances

U3. Substances can be hydrophobic  Hydrophobic:  “water fearing”  any substance which repels water or insoluble in water Ex: l]hospholipids, fatty acids, oils, non- polar molecules, methane, prop

A3. Transportation of Molecules SubstanceHigh or low relative solubility in water Mode of transport in an aqueous environment (no special mode means the substance dissolves directly and easily into water) GlucosePolar molecule/ high solubility No special mode of transport needed, dissolves directly into plasma Amino AcidsVarying polarity but all are reasonably soluble No special mode of transport, dissolve directly into plasma CholesterolLargely non-polar, very low solubility Transported by blood proteins with polar amino acids on the outside to give water solubility, non-polar amino acids internally bond to non polar cholesterol

A3. Transportation of Molecules SubstanceHigh or low relative solubility in water Mode of transport in an aqueous environment (no special mode means the substance dissolves directly and easily into water) FatsNon-polar fatty acid components, very low solubility Transported by blood proteins with polar amino acids on the outside to give water solubility, non-polar amino acids internally bond to non polar fatty acids OxygenTravels as O 2, low solubility Relatively low solubility in water and warm temps., haemoglobin is used to bind and transport oxygen Sodium Chloride Ionizes, high solubilityNo Special mode of transport needed, separates into Na + and Cl - ions in plasma

U2. Water Properties Review PropertyReasonConsequence Cohesion Hydrogen bonds hold water molecules together Water can travel in continuous columns; act as a transport medium Solvent Polar molecules of water can interact with other polar molecules Able to dissolve ions and large molecules with polar side chains; acts as an excellent transport medium and medium for metabolic reactions Thermal Water has a high heat capacity (lots of energy needed to break H bonds and change temp) Organism temp changes slowly; body fluid (blood) transports heat throughout Thermal Water has a high boiling point (lots of energy needed to break H bonds) Liquid at most temps life exists; medium for metabolic reactions Thermal Water has a high latent heat of vaporization as H bonds break acts as a coolant (sweating in animals and transpiration in plants)