BOTANY 160         MID-SEMESTER EXAM KEY       OCTOBER 18, 1995




I. Definitions (Choose 5; 4 points each)

     Leaf Area Index 
     Gross Primary Production
     Physiognomy 
     Holism
     Biome
     Littoral zone
     Thermocline
     Epilithic periphyton
     Insectivory
     Allochthonous



II. Short Answer (Choose 4; 10 points each)

     1. What is the distinction between collective and emergent
        properties in community ecology? Give an example of each.



     2. Give two physical/chemical properties of water and for
        each give an example of its importance for aquatic life.



     3. What are three ways that phytoplankton have evolved to
        stay in the euphotic zone of lakes?



     4. What is meant by the expression that water velocity in
        rivers is a double-edged sword for the organisms living
        there?



     5. What are the criteria used to define a wetland?



     6. What is the essence of the Raunkiaer classification of
        life forms?



     7. In soils the clay and humus components are said to have
        Cation Exchange Capacity. What is meant by this and what
        role does it play in plant growth?



     8. In the Northern Coniferous Forest biome the dominant
        plants are xerophytes. What are xerophytes and why do they
        dominate in this biome?


 III. Essay Question (CHOOSE 1; 40 points)



     1. Contrast and compare a typical river aquatic ecosystem to
        that of a lake. Bring into your discussion the structure and
        function of these systems, including the evolutionary
        adaptations of the dominant plants and algae, and the
        current paradigms of energy flow and nutrient cycling in
        these systems.



                                OR


     2.(A)Diagram the essential components of an ecosystem
          emphasizing the structural and functional aspects of
          ecosystems in general.

       (B)Using the above diagram as a framework discuss the
          essential differences between the Northern Coniferous
          Forest and the Eastern Deciduous Forest biomes.