Oceans/Gas Exchange

Based on Mader, Sylvia S. 1996. Biology - 5th Ed. WCB

and

Cox, G.W. 1997. Conservation Biology - 2nd ed. WCB

and

Levine, J.S. and K.R. Miller. 1994. Biology: Discovering Life. D.C. Heath

Reading: Chapters 17, 18 in Cox – Chapter 36 in Levine and Miller

1. Gas Exchange
2. 1. Plants - take in CO₂ at stomata
   2. 1. concurrent loss of water
      2. stomata close when water is scarce
   3. Animals - take in oxygen, release CO₂
   4. 1. need for O₂ proportional to:
      2. 1. volume
         2. metabolism
         3. activity
      3. must have sufficient surface area to allow oxygen in
      4. 1. not a problem for small organisms
         2. larger organisms:
         3. 1. evaginations (gills)
            2. invaginations (lungs, tracheae)
            3. ventilation
            4. 1. breathing
               2. ram ventilation
         4. special mechanisms:
         5. 1. countercurrent flow (Figure 36.4):

            2. O₂ concentration in water ----->

               100% 70% 40% 15%

               90% 60% 30% 5%

               <--- O₂ concentration in blood

            3.  
            4. hemoglobin and other pigments
            5. 1. binds oxygen in air or water, brings into body
               2. releases oxygen under warmer, acidic conditions
               3. 1. in muscles where CO₂ is released
      5. diffusion is at the basis of all respiration
   5. Gas exchange crucial for aquatic organisms
   6. 1. oxygen levels 5% of that in air
      2. compensation: Aquatic organisms are
      3. 1. slower
         2. smaller
         3. less active
         4. don’t use energy to stay in position (float)
      4. exceptions:
      5. 1. whales -
         2. 1. breathe air
         3. fish
         4. 1. swim constantly (ram ventilation)

1999 - read Chapters 17, 18 in Cox, prepare for test via study guide.

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