Food Chain and Food Webs Ms. McGrath Science 10

Food Chains Grass  grasshopper  robin  hawk Primary consumer: eat producers Herbivore: only eat plants Heterotroph: hetero = others, troph = food Producer: makes its own food through photosynthesis which uses energy from the sun Autotroph: auto = self, troph = food Secondary consumer Tertiary consumer Energy transfer (10% passed on at each step)

Definitions Omnivore: eats everything (plants and meat) Example: Humans, brown bears Carnivore: only eats meat Example: Lions Scavengers: eat dead things, don’t kill prey Example: Vultures, raccoons Decomposers: consume dead material and recycle (return) nutrients to the soil Example: 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?

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: components of an ecosystem that are non-living Example: soil, water, sunlight Biotic factors: components of an ecosystem that are, or use to be, living Example: 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?

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 Sustainable ecosystem: able to handle pressure and support many different organisms

Day 2 Questions Which type of organism is at the beginning of all food chains? Which organisms can eat all other organisms? In an ecosystem, the abiotic factors include…? 3 examples of decomposers are …? What is the importance of decomposers in an ecosystem? What is the principal source of energy for all ecosystems?