Big Idea 2: BIOLOGICAL SYSTEMS UTILIZE FREE ENERGY and MOLECULAR

Name ______Date ______Period _____ Properties of Water Raven Ch. 2 Big Idea 2: BIOLOGICAL SYSTEMS UTILIZE FREE ENERGY AND MOLECULAR BUILDING BLOCKS TO GROW, TO REPRODUCE AND TO MAINTAIN HOMEOSTASIS.

Essential Knowledge:  All living systems require constant input of free energy.  Organisms capture and store free energy for use in biological processes.  Organisms must exchange matter with the environment to grow, reproduce and maintain organization.  Organisms exhibit complex properties due to interactions between their constituent parts.  Interactions between molecules affect their structure and function.  Variation in molecular units provides cells with a wider range of functions.

Why are we studying water? ______

Chemistry of water

. H2O molecules form ______with each other  ______(δ+) attracted to ______(δ–)  creates a sticky molecule Elixir of Life Special properties of water 1. Cohesion & Adhesion Cohesion  Hydrogen bonding ______molecules  Water is “sticky”  Creates ______-Explain: ______ Drinking straw Adhesion

 Hydrogen bonding between H2O & ______ Meniscus  Capillary action- (explain: ______ Ex: water climbs up paper towel, cloth, xylem 1 Transpiration- built on cohesion & adhesion -Explain: ______

2. Good solvent

 ______makes H2O a good ______ ______dissolve ______creating ______

 polar H2O molecules surround ______and ______molecules

What dissolves in water?  ______

 substance that has an ______to H2O  polar or non-polar? Example: ______

What doesn’t dissolve in water?  ______

 Substances that ______to H2O  polar or non-polar? Example: ______

3. Lower density as a solid (Special Case of Ice):  Most (all?) substances are more dense when they are ______but not water…  Ice floats!  Hydrogen bonds form a ______

Why is “ice floats” important?  Oceans & lakes don’t ______ surface ice ______water below  allowing life to survive the winter  if ice sank…ponds, lakes & even oceans would freeze solid; in summer, only upper few inches would thaw  seasonal ______of lakes

 sinking cold H2O cycles nutrients in autumn 2 4. High Specific Heat (Heat Capacity)

. H2O ______in temperature  high specific heat (Water = _____)  gain a lot of energy to ______it up  lose a lot of energy to ______it down

. H2O ______temperatures on Earth (holds heat)

5. High Heat of Vaporization (Enthalpy)

. Heats & cools ______. Amount of heat absorbed to ______water at a ______temperature . Organisms rely on heat of vaporization to remove ______ Ex: ______

3 Ionization of water & pH  Water constantly ______

+ –  H splits off from H2O, leaving OH (H2O  ______+ ______)  if [H+] = [-OH], water is ______ if [H+] > [-OH], water is ______ if [H+] < [-OH], water is ______ pH scale  [Measure of] how ______or ______(alkaline) a solution is  ____  ____  ____

***Tenfold change in H+ ions

pH1  pH2 (10-1  10-2) ?--______times ______H+

pH8  pH7 (10-8  10-7) ?--______times ______H+

pH10  pH8 (10-10  10-8) ?--______times ______H+

Buffers & cellular regulation . pH of cells must be kept ~7  pH affects ______of molecules; shape of molecules affect ______ pH affects ______. ______control pH by  reservoir of ______ ______H+ when [H+] falls (carbonic acid)  ______H+ when [H+] rises (bicarbonate ion)