1 MINI SCIENCE NOTES Name : Lau Zhi Yi Class : 2 Emerald
2 Chapter 2 : Ecosystem 2.1 Energy Flow in an Ecosystem Do you know that the source of energy in all ecosystem originates from the Sun? Green plants convert light energy from the Sun into chemical energy through the process of photosynthesis. The chemical energy is transferred to primary consumers and then to secondary and tertiary consumers in the food chain and food web. Producer A producer is an organism that produces its own food through photosynthesis. Most plants are producer. For example, paddy plant and tomato plant. Paddy plant Tomato plant Primary consumer A consumer is an organism that eats another organism. Primary consumers are herbivores and omnivores that eat producers. For example, caterpillars and grasshoppers. Caterpillar Grasshopper Secondary consumer A secondary consumer, also known as primary carnivore is an omnivore and carnivore that eats the primary consumer. For example, chicken and frog. Chicken Frog Producers, Consumers and Decomposers
Tertiary consumer A tertiary consumer is a secondary carnivore that eats a secondary consumer. The size of a tertiary consumer is usually bigger than a primary or secondary consumer. For example, tiger and eagle. Tiger Eagle Decomposer A decomposer is an organism that breaks down dead animals and plants into simpler materials or nutrients. For example, mushroom and E.coli bacteria. This interaction is known as saprophytism. Mushroom E.coli bacteria Food Chain A food chain can be used to show the feeding relationship between organisms. Example: Oil palm Rat Snake Oil palm Producer Secondary consumer Primary consumer Tertiary consumer
Food Web The interconnection of a few food chains is called food web. Example: Rat Snake Oil palm Owl Squirrel Crow Rhinoceros beetle Producer Secondary consumer Primary consumer Tertiary consumer
Energy Flow in a Food Web ❖ As seen in the food chain, energy is also transferred from one organism to another organism in the food web. ❖ Some of energy is lost because it is used by the organism to move and carry out life process of respiration. ❖ Energy is also lost in the form of heat energy or chemical energy through undigested food. ❖ The diagram shows the relative number of organisms in each level ❖ Any changes to the population number in each level may caused imbalance ecosystem
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