Transcript Food Chains
Notes 1 – Food Chains SCI 10 Ecology Food Chains Grass grasshopperrobinhawk Producer: makes its own food through photosynthesis which uses energy from the sun -Autotroph: auto = self, troph = food -Primary Consumer: eat producers -Herbivore: only eat plants -Heterotrophs: hetero = others, troph = food Energy transfer (90% lost at each step) Secondary Consumer Tertiary consumer Other Definitions Omnivore: eats everything (plants and meat) Ex. Human, brown bears Carnivore: only eats meat Ex. Lions Scavengers: eat dead things ex. Vultures, raccoons Decomposers: consume dead material and recycle (return) nutrients to the soil ex: worms, bacteria, fungi Trophic Levels First trophic level = producers (plants) Second trophic level = primary consumers (herbivores) Third trophic level = secondary consumers (carnivores) Fourth trophic level = tertiary consumers In which trophic level do each of the following organisms belong?: grass crow coyote Maple tree bacteria snake mouse deer porcupine red squirrel seeds Producers Primary consumers Secondary consumers/ Decomposers Energy What is the primary source of energy for all food chains? The sun – without it we would not have food Food Web: many food chains interlinked Identify 3 food chains in the food web below deer snake wolf mouse grass rabbit frog shrubs hawk insect Abiotic vs. biotic Abiotic factors: non-living Ex: soil, water, a rock, sun Biotic factors: living or was living Ex: trees, birds, insects, bacteria Complete the diagram using the following terms : primary consumer (herbivore) , secondary consumer (carnivore), tertiary consumer, decomposers, second trophic level, first trophic level, producer, fourth trophic level, third trophic level Transfer of Energy -Food energy ingested by a consumer is used for many processes Only around ____ % is converted into body mass. Why do we rarely see more than 4 links in a food chain? Because energy decreases along the chain and so higher level consumers can’t be supported Organisms are interconnected Look at the following food chain : Grass deer wolf If the deer population increases, what would happen to: The grass population? The wolf population? The grass population would decrease The wolf population would increase because: More food increases reproductive rates (more babies) Eventually, the wolf population would start to decrease because food would run out Definitions Ecosystem: interactions among organisms and their environment Biotic factors: components of an ecosystem that are, or use to be, living i.e.: Abiotic factors: components of an ecosystem that are non-living i.e.: p.14 – Copy the Pyramid Fig 1.8 The greatest amount of energy is in the _______________, that of the _______________. A pyramid of numbers is used to represent the number of organisms at each trophic level The ___________ are the organisms that are usually the most numerous p.15 Look at this pyramid: Which 2 organisms are most numerous? p.16 – Copy Fig 1.11 ___________ combines the number and size of organisms It indicates how much living matter there is in a particular organism A pyramid of biomass: shows the biomass at each trophic level Which trophic level has the greatest biomass? Which trophic level has the smallest biomass? p.17 – Copy Fig 1.13 A pyramid of energy flow shows the total chemical energy at each trophic level Total energy decreases from producers to consumers – how? 90% of the energy from your food is lost to: respiration, heat production, waste production 10% of the energy from your food is used to produce new tissues and grow Calculate the Energy Transferred at Each Trophic Level Look at the following food chain : Grass Rabbit Snake Wolf Complete the table below Organism Grass receives 7400 kilojoules (kJ) or energy from the sun Available energy (kJ) Energy used (kJ) Energy stored (kJ) Notes 1 Questions 1. Which type of organism is at the beginning of all food chains? 2. Which organisms can eat all other organisms ? 3. In an ecosystem, the abiotic factors include…? 4. 3 examples of decomposers are …? 5. What is the importance of decomposers in an ecosystem? 6. What is the principal source of energy for all