1. Water and the Fitness of the Environment Chapter 3 Drops on plastic Paper clip

2. Molecule That Supports All of Life Cells are ~70–95% water Water is the main reason the Earth is habitable Water is versatile!

3. 75% of the Earths surface is water

4. water molecules and hydrogen bonding Water is a polar molecule: ▫opposite ends have opposite charges Note hydrogen bonds

5. Four emergent properties of water 1. Cohesion water molecules “stick” together transports water against gravity in all vascular plants Adhesion – water H-bonds to other substance Water molecules stick together

6. Adhesion

7. Water-conducting cells Adhesion Cohesion 150 µm Direction of water movement The video

8. Surface tension = Cohesion at water/air surface BASILISK Detergent breaks surface tension

9. 2. Water resists temperature change absorbs heat from warm air, releases to cool air Water can absorb more heat than air!

10. San Diego 72° 40 miles Pacific Ocean 70s (°F ) 80s 90s 100s Santa Barbara 73° Los Angeles (Airport) 75° Burbank 90° Santa Ana 84° Palm Springs 106° Absorption of heat by ocean cools the coast. At night, ocean releases heat to warm coast.

11. Water has a high specific heat = amount of heat needed to change T of 1 g of a substance by 1ºC Water is liquid over a broad range of temperatures

12. What happens when a copper pot is used to heat water? High specific heat = need to add more energy to water to raise its temperature! Substance c in cal/gm K or Btu/lb F Aluminum0.215 Copper0.0923 Brass0.092 Gold0.030 Lead0.0305 Silver0.0558 Zinc0.0925 Mercury0.033 Alcohol(ethyl)0.58 Water1.00 Granite0.19 Glass0.20

13. What IS heat? Heat is energy Heat =average amount of kinetic energy due to molecular motion Heat flows from more energetic area to less (coastline example) Faster moving molecule = hotter

14. Temperature measurement of intensity of heat Celsius degrees (°C)  Room T =  Body T =  Boiling =

15. Evaporation = transformation from liquid to gas Evaporative cooling ▫Surface is cooled as water evaporates ▫Sweating and evaporative coolingSweating The most energetic molecules are released as steam. The ones left are cooler because they have lost energy

16. 3. Ice floats Ice is less dense than liquid water ▫Water greatest density at 4°C If ice sank, all water would eventually freeze solid, making life impossible  Floating ice insulates, keeps water underneath liquid

17. Hydrogen bond Liquid water Hydrogen bonds break and re-form Ice Hydrogen bonds are stable The “locked” hydrogen bonds in ice space the molecules further apart, resulting in fewer molecules per equal volume of water hydrogen bonds in ice are more ordered in ice Most ectotherms cannot tolerate freezing Most ectotherms cannot tolerate freezing : north american wood frog

18. 4. Water is a great medium for dissolving substances like nutrients/wastes Solution=liquid that is a homogeneous mixture of substances ▫ solvent =dissolving agent  If water, the solution is aqueous ▫solute =substance that is dissolved  Ex. salt

19. hydrophilic substance has affinity for water hydrophobic does not

20. colloid =stable suspension of fine particles in a liquid Cant see in microscope, nevers settle out!

21. pH and solutions Changes in concentrations of H + and OH – can drastically affect cell pH =measure of the [H+] of a solution The pH scale is logarithmic pH = –log [H + ]

22. Effects of Changes in pH Acid = higher [H + ] = lower pH ▫Acidic solutions pH < 7 Base = higher [OH – ] Alkaline/basic solutions pH > 7 pH scale 0 – 14 ▫Most biological fluids pH ?

23. Acids and Bases HCl  H + + Cl - Acid or base? NaOH  Na + + OH - Acid or base?

24. Buffer Buffer =substance that resists changes in pH Baking soda NaHCO3 -  Na+ + HCO3- Bicarb ions can act either as an acid (donate H+) or as a base (accept H+ to form H2CO3).