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© 2009 Marshall Cavendish International (Singapore) Private Limited Questions to think about… How do plants get their food? What is the source of energy for animals? How is the Sun related to our energy sources? © 2009 Marshall Cavendish International (Singapore) Private Limited Source of energy for animals Let How us follow doesaapiece meal of baked potato’s provide us with journey energy? in the human body. © 2009 Marshall Cavendish International (Singapore) Private Limited Source of energy for animals 2. partially digested potato 3. The 4. In the the stomach, small intestine, digestion 1. In mouth, thefurther piecethe of potato travels down The the gullet toisthe takes is completely place. digested potato crushed a type potato is chewed into ainto mash. stomach. and of sugar mixed called with glucose. digestive juices. Saliva helps to digest theGlucose potato It then then enters moves down bloodstream to the small and slightly. It is the then swallowed. intestine. is transported to the cells in the body. © 2009 Marshall Cavendish International (Singapore) Private Limited Source of energy for animals • Energy is stored in food. • The food that we eat cannot provide our bodies with energy immediately. • It has to be digested first. • Glucose is the digested form of food that provides us energy. © 2009 Marshall Cavendish International (Singapore) Private Limited How do plants get their food? • Plants need energy to stay alive. • This energy comes from the food they make. • Plants make food in the presence of sunlight, through the process called photosynthesis. • During photosynthesis, energy from sunlight is used to combine carbon dioxide and water to make glucose and oxygen. • Glucose, a form of sugar, is food for the plant. © 2009 Marshall Cavendish International (Singapore) Private Limited How do plants get their food? • Photosynthesis water + carbon dioxide in the presence of sunlight glucose + oxygen In this way, energy from the Sun is passed on to plants. © 2009 Marshall Cavendish International (Singapore) Private Limited How do plants get their food? • Excess glucose is converted to starch and stored in different parts of the plant. • We get energy when we eat these plant parts. Some Otherplants plantsstore store Many plants store starch temporarily in their leaves. starch starchinintheir theirseeds. roots. Other plants store starch in their underground stems. lettuce potatoes soy beans carrots © 2009 Marshall Cavendish International (Singapore) Private Limited The Sun and our energy sources • When plant parts are eaten by animals, the energy stored in the plant parts is transferred to the animals. • Some animals eat plants only (plant-eaters) • These plant-eaters get their energy from plants. rabbit giraffe zebra © 2009 Marshall Cavendish International (Singapore) Private Limited The Sun and our energy sources • Other animals eat plants and animals (plant-and-animal eaters). • These plant-and-animal eaters get their energy from both plants and animals. man raccoon chicken © 2009 Marshall Cavendish International (Singapore) Private Limited The Sun and our energy sources • Some animals eat only other animals (animal-eaters). • These animal-eaters get their energy from the meat they eat. snake tiger © 2009 Marshall Cavendish International (Singapore) Private Limited The Sun and our energy sources • Although animals that eat only animals do not eat plants, the energy that they get can be traced back to plants. • Since plants make food from using energy from the Sun, the energy from the Sun is passed on from the plants to the plant-eaters. In this example, the energy from the grass is transferred to the planteater – the zebra. © 2009 Marshall Cavendish International (Singapore) Private Limited The Sun and our energy sources • Eventually, this energy is passed on from plant-eaters to animal-eaters. Here, is transferred Thus,energy food produced by from the plant-eater to the plants become the source animal-eater, as this of energy forsuch animals. lioness. © 2009 Marshall Cavendish International (Singapore) Private Limited © 2009 Marshall Cavendish International (Singapore) Private Limited