Year 9 Ecosystems: Food chains & food webs

Food Chains All energy in a food chain begins with the sun. This provides autotrophs (producers) e.g. plants, algae, etc., with the ability to create organic molecules (glucose) via photosynthesis. Energy flows from producers to herbivores (heterotrophs, consumers) through to carnivores via the organic molecules they obtain via feeding. (a heterotroph is a consumer) This is called a food chain. What is a producer? Worksheet Achieve p20-21

Food Chains A food chain can be represented using pictures or words, but it always needs arrows. The arrows show what is eaten by what and the flow of energy along the food chain. Food chains worksheet Achieve p26-27

Food Chains Where do decomposers fit into the food chain? Food chains worksheet Achieve p26-27

Food Webs Food chains are not the best way to describe the trophic relationships in most ecosystems because they are too simple. In reality, ecosystems usually involve many species that are connected in all sorts of ways. The place where I live: A freshwater habitat vid (up to 5 mins 30) Online exercise, build your own food web Food webs worksheet Achieve p28-29

Summary All food chains and food webs start with the sun. Arrows show the flow of energy through a food chain / food web. There are generally many relationships between different organisms in an ecosystem.