Figure 2-17

1. Figure 2-17

2. Lemonade Spring Yellowstone NP pH 2.6 Algal Growth!

3. Helicobacter pylori Bacterium that infects the stomach and duodenum, Causes dyspepsia, gastritis, 80% of stomach and 90 % of duodenal ulcers (and perhaps cancer).

4. Key points Water • What makes water a unique medium for life • Water is a good solvent • Water molecules are highly cohesive • Water has a high specific heat and high • heat of vaporization • Water is denser as a liquid than a solid

5. Key points Acids & Bases An acid is any solute that raises the concentration of H+ie acids give up H+ A base is any solute that lowers the concentration of H+ie bases acquire H+ Strong acids such as HCl dissociate quickly releasing large numbers of protons in to solution. Weak acids such as carbonic acid dissociate very slowly and may reassociate. Remember that free H+ do not exist in reality. In water the protons associate with water molecules. Thus the dissociation of water should be more accurately written as H2O + H2O H3O+ + OH- Water can act as both an acid and a base

6. Summary of Key Points Acidity/alkalinity is expressed using the expression pH = -log [H+] Most organisms like to live at a neutral pH but acidophilic and alkaliphilic organisms live at extremes of pH. Biological buffers help resist changes in pH, often by absorbing protons. In mammals they help maintain a constant pH in cells and their environment. In humans the pH of the blood is maintained partly by a buffering system that relies on Carbonic Acid-Bicarbonate Buffer system

7. Figure 2.3 The structure of atoms found in organisms

10. DHA

11. Lactose intolerance Lactose intolerance increases with increasing age. 2–3 y 6 y 9–10 y 0%, 0% 6% in European Americans 18% 30% 47% in Mexican Americans 25% 45% 60% in black South Africans 30% 80% 85% in Chinese and Japanese In one study of 24 Native Americans adults, all were lactose intolerant 45% of African American children are lactose intolerant.