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1 of 47© Boardworks Ltd 2008 PHOTOSYNTHESIS. 2 of 47© Boardworks Ltd 2008 How do plants make their own food? One of the raw materials that plants need.

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Presentation on theme: "1 of 47© Boardworks Ltd 2008 PHOTOSYNTHESIS. 2 of 47© Boardworks Ltd 2008 How do plants make their own food? One of the raw materials that plants need."— Presentation transcript:

1 1 of 47© Boardworks Ltd 2008 PHOTOSYNTHESIS

2 2 of 47© Boardworks Ltd 2008 How do plants make their own food? One of the raw materials that plants need to make food does come from the soil, the other comes from the air. What are these two raw materials? Plants use carbon dioxide and water to make their own food in a chemical reaction. What is the name of this reaction? carbon dioxide (from the air) water (from the soil)

3 3 of 47© Boardworks Ltd 2008 What is the name of the process? Plants make their food from carbon dioxide and water in a chemical reaction called photosynthesis. Oxygen gas is also made as a by-product of photosynthesis. glucose oxygen carbon dioxide (from the air) water (from the soil) The food made by photosynthesis is the sugar, glucose.

4 4 of 47© Boardworks Ltd 2008 Where does the energy come from? Plants need energy for photosynthesis to take place. The energy for photosynthesis comes from the Sun. Where in a plant does photosynthesis take place? glucose oxygen carbon dioxide (from the air) water (from the soil)

5 5 of 47© Boardworks Ltd 2008 Where does photosynthesis happen? Plant cells in the upper surface of leaves have chloroplasts which contain the green pigment called chlorophyll. It is chlorophyll, which absorbs light energy from the Sun, that enables plants to carry out photosynthesis. glucose oxygen carbon dioxide (from the air) water (from the soil) chlorophyll

6 6 of 47© Boardworks Ltd 2008 Photosynthesis Plants make their own food by a process called photosynthesis. The word equation for photosynthesis This equation can be read as: “Carbon dioxide and water, using light energy and chlorophyll, react to make glucose and oxygen” light energy chlorophyll carbon dioxide + wateroxygen + glucose

7 7 of 47© Boardworks Ltd 2008 What is needed for photosynthesis?

8 8 of 47© Boardworks Ltd 2008 What is the word equation?

9 9 of 47© Boardworks Ltd 2008 Photosynthesis Photosynthesis

10 10 of 47© Boardworks Ltd 2008 Water comes from the soil Carbon dioxide comes from the air Chlorophyll is a green pigment found in the chloroplast of leaves It traps light energy that is needed to make the glucose chloroplast contains chlorophyll

11 11 of 47© Boardworks Ltd 2008 The leaves are specially adapted for photosynthesis 1.Leaves are flat and thin - To absorb maximum light 2.Leaves have tiny pores called stomata - To allow CO 2 in and O 2 out 3.Leaves have chloroplasts - These contain chlorophyll - Chlorophyll traps light energy

12 12 of 47© Boardworks Ltd 2008 The Products of Photosynthesis 1.Glucose Used in respiration Stored as starch 2.Oxygen Used in respiration Released into the air – Animals then use it for respiration

13 13 of 47© Boardworks Ltd 2008 To show that a plant produces starch We need to show that a plant is making starch during the experiment First we must remove any starch that is already in the plant i.e. we must destarch the plant To destarch a plant It is placed in a dark cupboard for 48 hours (The plant uses up all its stored starch and it cannot make any more) During this experiment safety goggles must be worn!!!!!

14 14 of 47© Boardworks Ltd 2008 1.Cover some leaves with aluminium foil (This will act as our control) 2.Place plant in strong sunlight for several hours 3.Remove leaves from plant and boil for one minute to kill them

15 15 of 47© Boardworks Ltd 2008 3.Place leaves in alcohol to remove chlorophyll 3.Now place leaves in warm water to soften 4.Place leaves on white tile and add a few drops of iodine

16 16 of 47© Boardworks Ltd 2008 Results Iodine is a red/brown chemical If starch is present it turns blue/black LeafResultConclusion Leaf covered in foilNo colour changeNo starch found Uncovered leafTurns blue/blackStarch has been made during photosynthesis

17 17 of 47© Boardworks Ltd 2008 Testing a leaf for starch

18 18 of 47© Boardworks Ltd 2008 To show starch is produced

19 19 of 47© Boardworks Ltd 2008 The Control

20 20 of 47© Boardworks Ltd 2008 Quiz Quiz Exclude Q2

21 21 of 47© Boardworks Ltd 2008 Wordsearch Wordsearch

22 22 of 47© Boardworks Ltd 2008 Skool.ie lesson http://www.skoool.ie/content/skoool_learning/junior/lessons/science/plant_nutrition/flash/h-frame-ns6.htm Skool.ie assessment http://www.skoool.ie/content/skoool_learning/junior/assessments/science/plant_nutrition/flash/h-frame-ns6.htm

23 23 of 47© Boardworks Ltd 2008


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