Water Properties for Biology PDF

1.1 Structure of Water and hydrogen bonding Essential idea: Water is the medium of life. The cohesive nature of nature gives it surface tension. The surface tension in turn allows organisms such as pond skaters (above) to move across the surface. For pond skaters...

1.1 Structure of Water and hydrogen bonding Essential idea: Water is the medium of life. The cohesive nature of nature gives it surface tension. The surface tension in turn allows organisms such as pond skaters (above) to move across the surface. For pond skaters the surface of water is their habitat. The surface tension transmits vibrations from fallen invertebrates - this allows pond skaters to detect and locate their prey. Understandings, Applications and Skills Statement Guidance 2.2.U1 Water molecules are polar and hydrogen bonds form between them. 2.2.U2 Hydrogen bonding and dipolarity explain the Students should know at least one example of cohesive, adhesive, thermal and solvent properties a benefit to living organisms of each property of water. of water. Transparency of water and maximum density at 4°C do not need to be included. 2.2.U3 Substances can be hydrophilic or hydrophobic. 2.2.A1 Comparison of the thermal properties of water with Comparison of the thermal properties of water those of methane. and methane assists in the understanding of the significance of hydrogen bonding in water. 2.2.A2 Use of water as a coolant in sweat. 2.2.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.  1.1 U1 Water molecules are polar and hydrogen bonds form between them. Water molecules and their bonds Water (H2O) is made up of two hydrogen atoms covalently bound to an oxygen atom While this bonding involves the sharing of electrons, they are not shared equally The number of protons in each atom is different; oxygen atoms have 8 whilst hydrogen atoms have just 1 having more protons the oxygen atoms attract the electrons more strongly Thus the oxygen end of the Covalently bonded http://www.colorado.edu/physic molecule becomes slightlymolecules negative potential that have a slight charge are said to s/2000/applets/ and the hydrogen end becomes be polar h2ob.html slightly positive The slightly charged regions of the water molecule can attract other polar or Animated charged compounds tutorial on Water molecules can hydrogen associate via weak bonding hydrogen bonds Hydrogen bonds are transitory in nature – they http://programs.northlandcollege.edu/biol constantly form, break and ogy/biology1111/animations/ re-form hydrogenbonds.html  1.1 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. roperties of water molecules Nature of science: Use theories to explain natural phenomena - the theory that hydrogen bonds form Cohesion: between water molecules explains the properties of water. (2.2) This property occurs as a result The observable properties of water are explained by of the polarity of a water cohesion, adhesion, solvent and thermal properties, molecule and its ability to form which are in turn explained by hydrogen bonding. hydrogenhydrogen Although bonds bonds are weak the large number of bonds present (each water molecule bonds to four others in a tetrahedral arrangement) gives cohesive forces great strength Water molecules are strongly cohesive (they tend to stick to one another) Water droplets form because the cohesive Surface tension is caused by forces are the cohesive hydrogen bonding trying to pull resisting an object trying to the water penetrate the surface. into the smallest possible n.b. capillary action http://ib.bioninja.com.au/standard-l volume, a involves cohesion and evel/topic-3-chemicals-of-life/31-ch emical-elements-and.html sphere. adhesion and so dealt with under adhesion.  1.1.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. roperties of water molecules Nature of science: Use theories to explain natural phenomena - the theory that hydrogen bonds form Adhesion: between water molecules explains the properties of water. (2.2) This property occurs as a result of the polarity Water of a water molecule and its ability to form droplets hydrogen bonds stick to surface and Water molecules tend to stick to other seem to molecules that are charged or polar for similar defy gravity because of reasons that they stick to each other form Again similarly individual hydrogen bonds are because the adhesive weak, but large number of bonds gives forces that adhesive forces great strength bond them to the surface of Capillary action is the grass caused by the blade. combination of adhesive forces causing water to bond to a surface, e.g. the sides of a xylem vessel and the cohesive forces bonding water molecules together. Capillary action is helpful in the  1.1 U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. roperties of water molecules Nature of science: Use theories to explain natural phenomena - the theory that hydrogen bonds form Solvent: between water molecules explains the properties of Water can dissolve many organic and water. (2.2) inorganic substances that have charged or polar regions. The polar attraction of large quantities of Metabolic reactions happen most readily in water molecules can interrupt intra- solutions of water – water in cells dissolves molecular forces (such as ionic bonds) and the reactants /substrates resulting in the dissociation of the atoms Positive atoms, e.g. Na+ end up being Cells are mostly water therefore surrounded by the negative oxygen regions diffusion into and out of them happens of water molecules and the Cl- being most easily if the substance concerned surrounded by the positive hydrogen region is in solution, e.g. before oxygen diffuses of water molecules from the alveoli to the blood it dissolves Because of this water is often (wrongly) into the moist layer lining the alveoli. referred to as being the ‘universal solvent’, it is however a very good solvent for many substances. http://upload.wikimedia.org/wikipedia/commons/8/8b/ Alveoli.svg Soluble substances such as sucrose can be easily transported around the plant in the phloem. Once dissolved in the http://www.sumanasinc.com/ http://www.northland.cc.mn.us/ webcontent/animations/content/ water of the phloem the sucrose can be biology/Biology1111/animations/ propertiesofwater/water.html moved to where it is needed by mass dissolve.swf flow. What kind of bears dissolve in water? Polar Bears! https://upload.wikimedia.org/wikipedia/commons/0/ 1.1.U3 Substances can be hydrophilic or hydrophobic. hydrophilic This term is used to describe substances that are chemically attracted to water. ( water loving ) All substances that dissolve in water are hydrophilic, including polar molecules such as glucose, and particles with positive or negative charges such as sodium and chloride ions. Substances that water adheres to, cellulose for example, are also hydrophilic. A space filling molecular diagram of glucose showing the positive and negative charges http://www.middleschoolchemistry.com/img/content/multimedia/chapter_5/lesson_7/  1.1 U3 Substances can be hydrophilic or hydrophobic. hydrophobic This term is used to describe substances that are insoluble in water ( water fearing ) Molecules are hydrophobic if they do not have negative or positive charges and are nonpolar All lipids are hydrophobic, including fats and oils Hydrophobic molecules dissolve in other solvents such as propanone (acetone) http://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Water_and_oil.jpg  1.1 A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. ransport of molecules in the blood Blood plasma consists of mainly of water (95%) plus dissolved substances which it transports. Glucose polar molecule hence freely soluble carried by the blood plasma http://4.bp.blogspot.com/-71TuXJIWv8o/UChT59p73fI/AAAAAAAAAFY/ B1zkMgT-dlA/s1600/ Glucose.png  1.1.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. ransport of molecules in the blood Amino acids Positive and negative charges (due to the amine and acid groups) therefore soluble in water R group varies, can be polar, non-polar or charged R group determines the degree of solubility carried by the blood plasma There is an internal transfer of a hydrogen ion from the -COOH group to the -NH2 group to leave an ion with both a negative charge and a positive charge. n.b. the bullet points summarise what you need to know. The below chemistry gives a more complete understanding for those who want to know why. http://chemwiki.ucdavis.edu/Under_Construction/Chemguide_(Jim_Clark)/ Properties_of_Organic_Compounds/XIII._Amino_Acids_and_Other_Biochemistry /A._Amino_Acids/2._Acid-Base_Reactions_of_Amino_Acids  1.1.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. ransport of molecules in the blood Oxygen O=O Non-polar molecule Due to the small size of an oxygen molecule it is soluble in water, but only just water becomes saturated with oxygen at relatively low concentrations As temperature increases the solubility of oxygen decreases At body temperature (37 °C) very little oxygen can be carried by the plasma, too little to support aerobic respiration hemoglobin in red blood cells carry the majority of oxygen Hemoglobin has (4) binding sites for oxygen Hemoglobin https://upload.wikimedia.org/wikipedia /commons/thumb/3/3d/1GZX_Haemoglobin.png/480px-1GZX_Haemo globin.png  1.1.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. ransport of molecules in the blood Fats Large, non-polar molecules insoluble in water They are carried in blood inside lipoprotein complexes (in the plasma) Lipoprotein complex Outer layer consists of single layer of phospholipid molecules hydrophilic phosphate heads of the phospholipids face outwards and are in contact with water Cholesterol The hydrophobic hydrocarbon tails molecules are hydrophobic, apart face inwards and are in contact with from a small hydrophilic region at one end the fats cholesterol molecules are positioned in This is not enough to make cholesterol dissolve in water the phospholipid monolayer - They are carried in blood in hydrophilic region facing outwards lipoprotein complexes (in the Proteins are also embedded in the plasma) phospholipid layer (hence the name) http://chienlab.wikispaces.com/file/view/lipoprotein.jpg/45882185/  1.1.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. ransport of molecules in the blood Sodium Chloride ionic compound freely soluble in water dissolving to form sodium ions (Na+) and chloride ions (Cl-) carried in the blood plasma http://www.northland.cc.mn.us/biology/Biology1111/animations/  1.1.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. roperties of water molecules Nature of science: Use theories to explain natural phenomena - the theory that hydrogen bonds form between water molecules explains the properties of water. (2.2) Thermal: Water has a high specific heat capacity (4.2 Joules is required to raise the temperature of 1 g of water by 1°C) Water has a high heat of vaporisation (amount of energy needed to change from a liquid to a gas or vapour) http://www.sumanasinc.com/ Water has a high heat of fusion (amount of webcontent/animations/content/ propertiesofwater/water.html energy needed to be lost to change liquid water to ice) These properties are due to many hydrogen Water is used by Leaves bonds that need to be formed or broken to as a coolant. The heat change the temperature or state of water lost from leaves for Therefore the temperature of water remains evaporation prevents them over-heating. If the relatively stable leaves get too hot enzymes in their cells will start to denature. 1.1.A2 Use of water as a coolant in sweat.  1.1.A1 Comparison of the thermal properties of water with those of methane. paring and contrasting the properties of water and methan Methane Water Methane waste product of anaerobic respiration in certain prokaryotes living in anaerobic conditions Methane can be used as a fuel Formula CH4 H 2O If present in the atmosphere it Molecular mass 16 18 contributes to the Bonding Single covalent greenhouse effect. Key chemical property Polarity nonpolar polar that causes the major differences seen in the Density (g cm-3) 0.46 1 physical properties. Specific Heat Methanogenic Capacity 2.2 4.2 prokaryotes (J g-1 oc-1) can be found in Latent heat of swamps, wetlands, 760 2257 the guts of animals vapourisation (J g-1) (including cattle and Melting point (oC) -182 0 sheep) Boiling point (oC) -160 100 can also be found in https://commons.wikimedia.org/wiki/Water_molecule#mediaviewer/ waste dumps File:Water_molecule.svg https://upload.wikimedia.org/wikipedia