COMMUNITIES and ECOSYSTEMS Topic 5.1 IB Biology Miss Werba

TOPIC 5 – ECOLOGY and EVOLUTION 5.1 COMMUNITIES and ECOSYSTEMS 5.2 THE GREENHOUSE EFFECT 5.3 POPULATIONS 5.4 EVOLUTION 5.5 CLASSIFICATION J WERBA – IB BIOLOGY 2

THINGS TO COVER Ecological definitions Autotrophs & heterotrophs Consumers, detritivores & saprotrophs Food chains & webs Trophic levels Initial energy source for most communities Energy flow & energy transformations Energy pyramids Nutrient recycling J WERBA – IB BIOLOGY 3

ECOLOGICAL DEFINITIONS 5.1.1 ECOLOGICAL DEFINITIONS Ecology: The study of the relationships between living organisms and between organisms and the environment Species: A group of organisms that can interbreed and produce fertile offspring J WERBA – IB BIOLOGY 4

ECOLOGICAL DEFINITIONS 5.1.1 ECOLOGICAL DEFINITIONS Habitat: The environment in which a species normally lives or the location of a living organism Population: A group of organisms of the same species who live in the same area at the same time J WERBA – IB BIOLOGY 5

ECOLOGICAL DEFINITIONS 5.1.1 ECOLOGICAL DEFINITIONS Community: A group of populations living and interacting with each other in a particular area Ecosystem: A community (biotic) and its abiotic environment Tempe-rature Light Water Humidity pH Nutrients Wind Tides Turbidity J WERBA – IB BIOLOGY 6

CLASSIFYING ORGANISMS: Source of Energy 5.1.2 CLASSIFYING ORGANISMS: Source of Energy Autotroph: An organism that synthesises its organic molecules from inorganic substances Photosynthesis Heterotroph: An organism that obtains its organic molecules from other organisms Digestion J WERBA – IB BIOLOGY 7

CLASSIFYING ORGANISMS: Manner of Consumption 5.1.3 CLASSIFYING ORGANISMS: Manner of Consumption Producer: Do not consume! An autotroph Produces its own organic matter J WERBA – IB BIOLOGY 8

CLASSIFYING ORGANISMS: Manner of Consumption 5.1.3 CLASSIFYING ORGANISMS: Manner of Consumption Consumers: An organism that ingests other organic matter that is living or recently killed Classified by what they eat: can be herbivores, omnivores or carnivores Also classified according to their level in the food chain: can be primary, secondary or tertiary consumers J WERBA – IB BIOLOGY 9

5.5.2 DIET MISS J WERBA - TERM 4 2010 10

5.5.2 DIET MISS J WERBA - TERM 4 2010 11

5.5.2 MISS J WERBA - TERM 4 2010 12

CLASSIFYING ORGANISMS: Manner of Consumption 5.1.3 CLASSIFYING ORGANISMS: Manner of Consumption Decomposers: organisms that decompose organic material eg. bacteria and fungi Detritivores An organism that ingests non-living organic matter Saprotroph An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion J WERBA – IB BIOLOGY 13

5.1.4-5.1.8 FOOD CHAINS & WEBS The feeding relationship between species in an ecosystem is represented as a food chain. The transfer of energy and matter are represented by arrows: they point in the direction of energy flow ie. to the eater! J WERBA – IB BIOLOGY 14

5.1.4-5.1.8 FOOD CHAINS & WEBS Trophic level: the position that an organism occupies in a food chain or web In general: 1st TL = producer or autotroph 2nd TL = primary (1°) consumer, first-order consumer or herbivore 3rd TL = secondary (2°) consumer, second-order consumer or carnivore J WERBA – IB BIOLOGY 15

5.1.4-5.1.8 FOOD CHAINS & WEBS Food chains represent a linear relationship between organisms. Food webs represent interconnected relationships between organisms. Food webs are more realistic as there is rarely one predator to any one prey. J WERBA – IB BIOLOGY 16

FOOD CHAINS & WEBS Example: Food Webs Example: Food Chains 5.1.4-5.1.8 FOOD CHAINS & WEBS Example: Food Webs Example: Food Chains Water weed  Pond Flies  Frog  Kingfisher Carrot plant  Carrot fly  Flycatcher  Sparrow hawk Bushgrass  Impala  Cheetah  Lion Buckwheat  Gopher  Gopher snake  Red tailed kite J WERBA – IB BIOLOGY 17

ENERGY FLOW Command term: STATE 5.1.9-5.1.11 ENERGY FLOW Command term: STATE Sunlight is the initial energy source for most communities. Autotrophs convert light energy into organic matter via photosynthesis Heterotrophs consume this organic matter J WERBA – IB BIOLOGY 18

ENERGY FLOW Command term: STATE 5.1.9-5.1.11 ENERGY FLOW Command term: STATE Only ~10% of the energy is passed from one trophic level to the next The rest is lost! How is it lost? heat used in cellular respiration trapped in bones/faeces, etc J WERBA – IB BIOLOGY 19

5.1.9-5.1.11 ENERGY FLOW Because 90% of the energy is lost, it has a limiting effect on the number of organisms that can exist in a food chain. Results in competition for resources Therefore, fewer organisms can be supported in each successive trophic level. J WERBA – IB BIOLOGY 20

5.1.12 ENERGY PYRAMIDS Used to represent the amount of energy at each level of a food chain Appear as a pyramid because higher trophic levels always have ~90% less energy than preceding levels. The units are kJ/m2/yr J WERBA – IB BIOLOGY 21

NUTRIENT RECYCLING Command term: STATE 5.1.13 – 5.1.14 NUTRIENT RECYCLING Command term: STATE Energy can enter and leave an ecosystem – energy is not recycled! Conversely, nutrients have to be recycled through ecosystems. Decomposers (saprotrophic bacteria and fungi) recycle nutrients by returning them to the soil for plants to use. J WERBA – IB BIOLOGY 22

5.1.13 – 5.1.14 NUTRIENT RECYCLING C H2O N J WERBA – IB BIOLOGY 23

THE CARBON CYCLE Linked closely to Topic 5.2 - The Greenhouse Effect 5.1.13 THE CARBON CYCLE Linked closely to Topic 5.2 - The Greenhouse Effect Carbon is removed from the environment by: Photosynthesis, absorption in seawater, formation of carbonate rocks, use of carbonates in the shells of shellfish Carbon is introduced to the environment by: Respiration, volcanic eruptions, burning fossil fuels, breakdown of carbonates, deforestation Currently, the human race cannot remove carbon as readily as we are introducing it…increasing CO2 levels in the atmosphere and causing the Greenhouse effect J WERBA – IB BIOLOGY 24

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V = 500 kg, W = 600 kg, X = 5000 kg, Y = 50 kg, Z = 5 kg Sample questions Q1 In an area of an ecosystem, a biologist estimated the following biomasses (V to Z represent populations of particular species): V = 500 kg, W = 600 kg, X = 5000 kg, Y = 50 kg, Z = 5 kg Which of the following represents a possible food chain in this ecosystem? V ➝ W ➝ X ➝ Y Z ➝ Y ➝ V ➝ X Z ➝ Y ➝ X ➝ W X ➝ V ➝ Y ➝ Z J WERBA – IB BIOLOGY 26

seagrass (pop1) ➝ fish (pop2) ➝ pelicans (pop3) Sample questions Q2 seagrass (pop1) ➝ fish (pop2) ➝ pelicans (pop3) The diagram shows three populations that make up a food chain. If a new predator moves in that also feeds on fish, what might happen to the numbers in the three populations? Numbers in all three populations decline. Numbers in population 2 decline but 1 and 3 increase. Numbers in population 1 increase but 2 and 3 decline. Numbers in population 2 decline but 1 and 3 stay the same. J WERBA – IB BIOLOGY 27

Sample questions A1. D A2. C J WERBA – IB BIOLOGY 28

Sample questions Q3 Identify the producers, primary consumers, and top-order consumer. Draw a food chain for this food web that shows the seal in the position of: i. secondary consumer ii. tertiary consumer Use an example from this food web to explain why food webs are more stable than food chains. J WERBA – IB BIOLOGY 29

Sample questions A3 Producers: algae (phytoplankton) Primary consumers: zooplankton Top-order consumer: humans i. secondary consumer algae  zooplankton  seal  human, or algae  zooplankton  seal  husky ii. tertiary consumer algae  zooplankton  fish  seal  human, or algae  zooplankton  fish  seal  husky Multiple interactions are shown; alternative energy sources would be available if a food chain was interrupted. J WERBA – IB BIOLOGY 30