<p> Name ______Period ______AP Biology</p><p>Water Essay Grading Rubric</p><p>The unique properties (characteristics) of water make life possible on Earth. Select three properties of water and for each property,</p><p> a) identify and define the property and explain it in terms of the physical/chemical nature of water. b) describe one example of how the property affects the functioning of living organisms.</p><p>Identification - 1 pt Definition – 1 pt Elaboration – 1 pt Example – 1 pt polarity unequal charge electronegativity, Hd+, Od-, unequal sharing distribution tetrahedron, various Hydrogen bonding weak, intermolecular, electrostatic attraction various transient, attraction between Hd+ and Od- Cohesion Attraction of water H-bonding explained Transpiration, surface molecules for each other tension Surface tension Resistance to being H-bonding explained Water walking, water stretched striders, water held by soil particles Adhesion Attraction of water H-bonding explained Capillary action, molecules for other transpiration molecules High specific heat Absorbs 1 cal/g/C (or K) Water temp changes Moderates temperature slowly effects High heat of vaporization Energy required for liquid 540 cal/g/C, breaking H- Sweating, surface cools, to change to gas bonds coolant, high boiling point, water cycle/rain, transpiration Versatile solvent Dissolves many Dissolves by ionization Any valid biological compounds example Unusual phase change Solid>liquid>gas Ice floats (less dense), Nutrient upwelling, change crystal lattice, most dense in thermal mixing, at 4C, farther apart, more insulation layer of ice on H-bonds ponds Dissociation/ ionization 2H2O<> H3O+ + OH- pH scale based on H2O, Specific cellular or H20 <> H+ + OH- H2O pH = 7 (neutral) organismal example, electron source in photosynthesis, hydrolysis reactions Incompressibility Resists changes in volume H-bond influence Hydrostatic skeleton, due to pressure amniotic fluid, blood pressure, turgor Viscosity Resistance to flow Fish swimming, aquatic propulsion Poor conductivity Ability to allow e- flow Requires conducting Electric fish, eel solutes</p>