HTML University

Science Dept.

Biology BIO 100
Ecology

1. Definitions
   1. Abiotic: The Physical Environment

   2. Biotic Community: A Group of Organisms Inhabiting a Common Environment and Interacting with Each Other

   3. Ecosystem: Abiotic and Biotic

   4. Population: Of the Same Species

   5. Ecology: Area of Science Concerned with the Relationships of Organisms to One Another and to Their Environment

   6. Niche: The "Business" of the Organism; Each Species Fits into Its Community in a Unique and Functional Way

   7. Habitat: The Place of "Business" of the Organism; The Specific Part of a Community in which Each Organism Lives

2. The Ecosystem: The Biotic and Abiotic Environments
   1. Energy Flow: From Organism --> Organism (One Direction)

   2. Nutrient Cycling: Materials Are Cycled
      1. Organic Reservoir
         
      2. Inorganic Reservoir

3. Energy Flow
   1. C₆H₁₂O₆, A Large Molecule Is Synthesized from Smaller Molecules Found In Air, Soil and Water. Organisms Capable of Performing these Syntheses Are Autotrophs
      1. Autotrophs = Producers = Plants and Algae

      2. Source = Sun

      3. Method Is Photosynthesis : Involves O₂ and Carbon C Cycles

      4. N. B. After Photosynthesis, Metabolic Processes Take Place to Convert these Simple Sugars or Monosaccharides into More Complex Sugars, Fats and Proteins

   2. Energy and Material Is then Transferred to Consumers
      1. These Are Known as Heterotrophs or Consumers

      2. Primary Consumers Are Herbivores

      3. Secondary Consumers Are Carnivores, Parasites, and Scavengers

      4. Gross Primary Productivity = GPP

      5. Net P P = Gross P P - Autotrophic Respiration

   3. Recycling of Nutrients
      1. Reducers = Earthworms, Some Arthropods and Microarthropods

      2. Decomposers = Bacteria and Fungi: It Is through Decomposition that Nutrients Are Returned to the Environment, Otherwise Life Would Cease. They Are in the Organic Layer of the Soil and at the Bottom of Ponds and Lakes

      3. Summary
         1. Producers

         2. Consumers

         3. Reducers and Decomposers

      4. Each Group Derives Energy from the Group Proceeding It in the Chain of Events and these Represent the Trophic Levels

      5. The Movement of Energy from One Trophic Level to Another Is Never 100% Effective. Perfect Efficiency is Never Achieved and Energy is Lost from the System

4. Food Chains and Webs
   1. Flow of Energy from One Trophic Level to Another Is Called a Food Chain
      1. Plants --> Deer --> Cougar

      2. Crops --> Mice --> Hawks and/or Coyotes, Foxes

   2. Food Web: Interrelated Food Chains Make Up a Food Web

5. Chemical Cycles
   1. Oxygen Cycle
      1. Needed in
         1. Sugars, Fats, Protein
            
         2. Oxidation of Foods

      2. Inorganic Reservoirs
         1. Atmosphere As O₂, CO₂
            
         2. Rocks to a Lesser Extent

      3. Recycling
         1. Respiration: O₂ + Sugars --> CO₂ + H₂O
            
         2. Photosynthesis: CO₂ + H₂O --> O₂ + Sugars

   2. Carbon Cycle
      1. Needed in
         1. Sugars, Fats, Protein

      2. Inorganic Reservoirs
         1. Atmosphere As CO₂
            
         2. Rocks As Carbonates, CO₃^2-

      3. Recycling
         1. Respiration: O₂ + Sugars --> CO₂ + H₂O
            
         2. Photosynthesis: CO₂ + H₂O --> O₂ + Sugars
            
         3. Combustion: O₂ + Cellulose --> CO₂ + H₂O

   3. Nitrogen Cycle
      1. Needed in
         1. Sugars, Fats, Amino Acids in Proteins

         2. DNA, RNA, ATP

      2. Inorganic Reservoirs
         1. Atmosphere As N₂
            
         2. Rocks to a Lesser Extent, As NO₃^1-, Nitrates

      3. Recycling
         1. 78% of Air Is N₂ by Volume
            
         2. N₂ Is Not Directly Usable by Higher Plants
            
         3. NO₃^1- or Nitrates Can Be Used by Higher Plants
            
         4. Lightning, to a Limited Extent, Can Change N₂ --> NO₃^1-
            
         5. The Real Heroes
            1. Some Blue-Green Algae and Bacteria Can Change N₂ --> Amino Acids
               
               • Rhizobium: Symbiotic
                 
               • Azotobacter: Free Livivng
                 
               • Nostoc: Free Livivng
                 
               • Clostridium: Free Livivng
                 
            2. Ammonification Bacteria Change Amino Acids --> Ammonia, NH₃ or Ammonium, NH₄¹⁺
               
            3. Nitrosomonas : NH₃ --> NO₂^1-, Nitrite
               
            4. Nitrobacter : NO₂^1- --> NO₃^1-, Nitrate
               
            5. Denitrification Bacteria Can Convert N Compounds to N₂

   4. Phosphorus Cycle
      1. Needed in
         1. ATP, DNA, RNA, Skeletal Materials

      2. Inorganic Reservoirs
         1. Rock Formations as PO₄^3-, Phosphates, in Apatite, Bone
            
         2. How Can Phosphates Be Returned from the Sea?

      3. Eutrophication Vs Cultural Eutrophication

6. Reservoirs for Nutrients
   1. Biological
      1. C, H, O, N
         
      2. P, K, S, Ca, Mg, Na

   2. Inorganic
      1. The Atmosphere
         1. C, H, O, N
            
         2. S to a Lesser Extent

      2. Rocks
         1. P, K, S, Ca, Mg, Na
            
         2. C, H, O, N

7. Biological Magnification