13/07/2019 1.What do you need to stay alive? 2.What can provide the substances for life? 3.What do plants need to produce food? Starter Activity MISSION – LIFE SUPPORT Write your answer (10 seconds) Pass paper to partner Write something different

13/07/2019 Plants and Photosynthesis Explain why chlorophyll and light are necessary for photosynthesis Think creatively to produce a test for the presence of starch in a leaf

Things needed for photosynthesis 13/07/2019 SUNLIGHT Gives the plant energy CHLOROPHYLL The green pigment where the chemical reactions happen WATER Travels up from the roots CARBON DIOXIDE Enters the leaf through small holes (stomata) on the underneath

Photosynthesis equations 13/07/2019 Sunlight Carbon dioxide + water glucose + oxygen (food) 6CO2 + 6H20 C6H12O6 + 6O2 Chlorophyll Sunlight Chlorophyll Taken in through holes (stomata) in the leaves Stored as starch in leaves, roots, stems Taken in through the roots Question – How do we know that light is needed for photosynthesis?

Method for starch test: 13/07/2019 1) Cover up part of the leaf using aluminium foil What effect does this have on the plant? Stops light reaching the leaf 2) Place leaf in boiling water [1 minute] What does this do to the leaf? to kill the cell and tear open the cell membranes so the iodine stain can easily enter the cells Place leaf in boiling alcohol (ethanol) [5 minutes] What effect does this have on the leaf? to remove the green chlorophyll so the final results can be clearly seen

Method for starch test: 13/07/2019 4) Dip leaf into warm water What effect does this have? to remove the alcohol so the iodine stain can penetrate the leaf 5) Cover leaf with iodine solution to test for the presence of starch What do you see? Draw and explain your results Iodine turns starch blue-black Those parts of the leaf that stain blue-black contain starch Those parts that are yellow-brown (the colour of the iodine stain) do not have starch

Photosynthesis happens in the “palisade” cells in the leaf: 13/07/2019 Photosynthesis happens in the “palisade” cells in the leaf: Palisade cells

Close up on a palisade cell: 13/07/2019 Cell wall Cell membrane Chloroplasts (containing chlorophyll) Large vacuole Nucleus Cytoplasm

Chloroplast Chlorophyll Photosynthesis summary 13/07/2019 Chloroplast These are small structures that vary in number and size. They contain a green pigment called chlorophyll. LIGHT Chlorophyll The chlorophyll traps sunlight and uses this energy to drive the process of photosynthesis. Photosynthesis is the name of the chemical reaction that produces the plant’s food. Therefore, Chloroplasts are where a plant makes its own food.

NO LIGHT, NO PHOTOSYNTHESIS, NO STARCH! Results: 13/07/2019 The parts of the leaf which have been photosynthesising should have turned black. This shows that the part of the leaf which was covered up has not been photosynthesising, because it had no light. NO LIGHT, NO PHOTOSYNTHESIS, NO STARCH!

TRUE or FALSE 13/07/2019 Both leaves turned blue-black because both leaves have been photosynthesising. Only the leaf that had been in the dark turned blue-black because photosynthesis happens in the dark. Starch is made in leaves that are photosynthesising. Photosynthesis only happens in the light.

TRUE or FALSE 13/07/2019 A positive test for starch in a leaf is that iodine solution turns blue-black. Chlorophyll is a green pigment in plant cells that absorbs water. Light is not needed for a plant to produce oxygen and glucose. Light is essential for photosynthesis and provides the energy to drive the reaction. Alcohol removes chlorophyll from the leaf so the results of the starch test can be clearly seen. Plants make food (glucose) and oxygen which are essential for life. I will make the mission a success because I know what is essential for photosynthesis.

13/07/2019 Plants and Photosynthesis Explain why chlorophyll and light are necessary for photosynthesis Think creatively to produce a test for the presence of starch in a leaf

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Root hair cells 13/07/2019 Plant roots are made of “root hair cells” which have two features that help them to take in water and nutrients: Root hair cells Large surface area Thin cell membrane

Using light Plants need water to do the following: Produce glucose 13/07/2019 Plants need water to do the following: Produce glucose Enable transport of minerals Form fruits Enable growth Keep the leaves cool

Photosynthesis and Respiration 13/07/2019 In earlier work we looked at respiration: Glucose + oxygen water + carbon dioxide Photosynthesis is the reverse of respiration: Water + carbon dioxide glucose + oxygen