TOPIC 4.2 ENERGY FLOW

Transcription

1 TOPIC 4.2 ENERGY FLOW

2 4.2 A Food Chains

3 INTRO IB BIO 4.2 Recall from Topic 4.1 that ecologists study organisms using the 3 levels of organization shown below.

4 IB BIO 4.2 In most ecosystems, sunlight is 4 U1: Most ecosystems rely on a supply of energy from sunlight. the initial energy source for all organisms. Three types of autotrophs are able to use this energy to make carbon compounds: Plants Algae Producers Cyanobacteria Collectively, these organisms are known as producers.

5 IB BIO U2: Light energy is converted to chemical energy in carbon compounds by photosynthesis. Producers convert light energy into chemical energy through the process of photosynthesis. Carbon Dioxide + Water Glucose + Oxygen The light energy absorbed is used to form the chemical bonds in newly-synthesized carbon compounds

6 IB BIO Chemical energy from photosynthesis passes from producers to U3: Chemical energy in carbon compounds flows through food chains by means of feeding. consumers (heterotrophs) through consumption. Food Chains Consumers Food chains are diagrams that use arrows to show the flow of energy through ecoystems. Since producers directly absorb light, they form the base of every chain.

7 IB BIO Food webs are diagrams that show the interactions of various food U3: Chemical energy in carbon compounds flows through food chains by means of feeding. chains in an ecoystem. Note that producers are always at the base. Food Web

8 4.2 B Energy Loss

9 IB BIO Organisms obtain energy from U4: Energy released from carbon compounds by respiration is used in living organisms and converted to heat. compounds using cell respiration. The ATP that is made is used for life processes such as: Molecule synthesis Active transport of molecules Internal transport of substances within vesicles Exothermic The processes of making/using ATP are exothermic, which means energy is released as heat.

10 This heat is then emitted into the atmosphere and eventually lost from the ecosystem as a whole. IB BIO 4.2 Organisms are not able to convert heat to other types of energy. 10 U5: Living organisms cannot convert heat to other forms of energy. U6: Heat is lost from ecosystems. As a result, heat is released from their bodies into the environment.

11 IB BIO 4.2 The diagram to the left shows 11 U5: Living organisms cannot convert heat to other forms of energy. U6: Heat is lost from ecosystems. the flow of two essential components of an ecosystem: Energy (pink) Passed between organisms, however some is lost at each trophic level Nutrients (blue) Passed between organisms and not lost from the system. This includes organic matter and inorganic nutrients.

12 IB BIO The amount of energy available at each U7: Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels. trophic level determines the amount of biomass that can be present. As the energy at each level decreases, so does the overall population. Approx. 90% of energy is lost every level. As a result, the length of food chains is restricted. Food chains are usually contain 3-4 species.

13 IB BIO Pyramids of energy are diagrams that depict the energy present at Skills S1: Quantitative representations of energy flow using pyramids of energy. trophic levels. Since 90% of energy is lost at each level, the pyramid has a stepped shape overall. Pyramid of Energy

14 REVIEW IB BIO State the primary source of energy in most 14 ecosystems. 2. Describe how light energy is converted to chemical energy. 3. Draw an example food chain consisting of 5 named organisms. 4. Outline the loss of energy in an ecosystem. 5. Describe the relationship between energy loss and food chain length. 6. Define energy pyramid.