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Leaves Leaves are like small factories that produce food for the plant. Different parts of the leaf have different jobs. The veins in a leaf are bundles of tiny tubes that carry water and minerals to the leaf and return food from the leaf to the rest of the plant. Veins also help to support the leaf. © Boardworks Ltd 2003 Leaves © Boardworks Ltd 2003 Photosynthesis Leaves are green because they contain small bodies in the cells called chloroplasts. The chloroplasts contain a green pigment called chlorophyll. This green material gives the leaf its colour. With the help of chlorophyll and energy from the sun, a leaf can change lifeless substances into food. This process is called photosynthesis. Plants need water (H2O) and carbon dioxide (CO2) to make food through the process of photosynthesis. The water is gathered by the plant's roots. Carbon dioxide is gathered from the air through the stomata. © Boardworks Ltd 2003 Photosynthesis (continued) The leaf uses chlorophyll and sunlight to change the water and carbon dioxide into oxygen and glucose (sugar). This sugar is mixed with water and sent to other parts of the plant to be used by the plant as food. The oxygen is released into the air through the stomata. This is usually written as: Carbon + water Light Chlorophyll Glucose + oxygen This is usually read as carbon dioxide plus water in the presence of light and chlorophyll produces oxygen and sugar glucose. © Boardworks Ltd 2003 Photosynthesis summary Chloroplast They contain a green pigment These are small structures called chlorophyll. that vary in number and size. LIGHT Chlorophyll The Photosynthesis chlorophyll traps is thesunlight name of the Therefore, Chloroplasts arethe where and chemical uses this reaction energy that to produces drive the a plant makes its own food. process ofplant’s photosynthesis. food. © Boardworks Ltd 2003 Photosynthesis We know that plants make their own food from sunlight. They are the producers in the food chain. This is done in the green parts of the plant, e.g. upper surface of the leaves. The reaction for this is: CARBON DIOXIDE + Taken in through holes in the leaves WATER Taken in through the roots With light and FOOD (GLUCOSE) Made byphotosynthe sis and stored as starch in leaves, roots, stems, etc. + OXYGEN waste product exhaled + ENERGY USEFUL! chlorophyll © Boardworks Ltd 2003