OPTION C.2 COMMUNITIES & ECOSYSTEMS

Transcription

1 OPTION C.2 COMMUNITIES & ECOSYSTEMS

2 C.2 A Energy Flow

3 INTRO IB BIO C.2 3 Recall from Topic 4.2 that 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.

4 IB BIO C.2 4 Understandings U1: Most species occupy different trophic levels in multiple food chains. Trophic levels describe a species position in a food chain. The diagram to the left shows trophic levels in an aquatic and a terrestrial food chains. Trophic levels include: 1 st level = producers Trophic Level 2 nd level = primary consumers 3 rd level = tertiary consumers 4 th level = quaternary consumers

5 IB BIO C.2 5 Trophic relationships in a community can be complex and web-like Understandings U2: A food web shows all the possible food chains in a community. as many consumers feed on several species. Food webs are diagrams that show the interactions of various food chains. Food Web

6 IB BIO C.2 6 Most species occupy different trophic levels in multiple food chains. Understandings U1: Most species occupy different trophic levels in multiple food chains. For example, in this food web, the leopard seal is a tertiary or quaternary consumer depending on which food chain is observed. Food Web

7 IB BIO C.2 7 Understandings U3: The percentage of ingested energy converted to biomass is dependent on the respiration rate. In ecology, productivity refers to the rate at which biomass is generated and is measured in mass per area time (e.g. kg m -2 yr -1 ). Biomass is the total mass of dry organic weight in an area. Productivity Biomass

8 IB BIO C.2 8 Understandings U3: The percentage of ingested energy converted to biomass is dependent on the respiration rate. Primary production results from the synthesis of biomass by autotrophs from inorganic molecules (photosynthesis). Productivity Biomass

9 IB BIO C.2 9 Understandings U3: The percentage of ingested energy converted to biomass is dependent on the respiration rate. Primary production results from the synthesis of biomass by autotrophs from inorganic molecules (photosynthesis). Productivity Biomass Secondary production results from the production of biomass by consumers. This is driven by the transfer of organic matter between trophic levels (ingestion).

10 IB BIO C.2 10 Understandings U3: The percentage of ingested energy converted to biomass is dependent on the respiration rate. Energy ingested by consumers can be used for life processes or converted into biomass. The percentage of ingested energy converted to biomass depends on the rate of respiration. Productivity Biomass As discussed in Topic 2.8, in cell respiration organic molecules are broken down to produce ATP which fuels metabolic reactions.

11 IB BIO C.2 11 Production in an area can be described in two different ways: Understandings U3: The percentage of ingested energy converted to biomass is dependent on the respiration rate. Gross production = total amount of biomass produced per unit area per unit time Productivity Biomass Gross/Net Production Net production = Gross production - respiration

12 IB BIO C.2 12 Understandings U3: The percentage of ingested energy converted to biomass is dependent on the respiration rate. Gross production in an ecosystem is affected by many factors including space availability, rain, temperature and the stage of succession (see C.2 C). Productivity Biomass Gross/Net Production

13 IB BIO C.2 13 Skills S1: Comparison of pyramids of energy from different ecosystems. As shown in the graph below, net primary productivity varies between ecosystems. This is a result of varying environmental conditions as well as the organisms involved. Productivity Biomass Gross/Net Production

14 1. Euglena is a unicellular organism that feeds on bacteria and uses CO2 as a carbon source. Which describes the nutrition of this organism? a) Autotrophic only b) Heterotrophic only c) Saprotrophic only d) Autotrophic and heterotrophic 2. How is energy passed from one trophic level to the next? I. Food II Light III Heat a. I only b. I and II only c. II and III only d. I, II and III

15 1. What are the TWO major categories of organisms related to how they obtain energy? 2. What are the TWO methods autotrophs use to fix carbon into forms organisms can use? 3. List the types of heterotrophs.

16 IB BIO C.2 16 Applications A1: Conversion ratio in sustainable food production practices. In food production, feed conversion ratio is the food input in grams needed to produce a certain biomass. For example, if 150 grams of feed are needed to produce 120 grams of mass, the ratio is Productivity Biomass Feed Conversion Ratio

17 IB BIO C.2 17 Applications A1: Conversion ratio in sustainable food production practices. As shown in the graph, some livestock have a significantly higher ratio than others. The consideration of conversion ratios is necessary when establishing sustainable food production practices. Productivity Biomass Conversion Ratio

18 IB BIO C.2 18 Applications A1: Conversion ratio in sustainable food production practices. Farmed fish have a low ratio as a result of being fed protein meal instead of plant matter (like cattle). Since this is easier to digest, less waste is produced and conversion to biomass is more efficient. Productivity Biomass Conversion Ratio

19 REVIEW IB BIO C Define trophic level. 2. Define food web. 3. Outline the reason species can occupy multiple trophic levels. 4. Define productivity. 5. Differentiate between primary and secondary productivity. 6. Outline the effect of respiration rate on biomass accumulation in consumers.

20 VIDEOS IB BIO C.2 Bozeman Science: Energy Flow in Ecosystems 20 Feed Conversion Efficiency Trial