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2015/4/30 Photosynthesis 光合作用 香港道教聯合會青松中學 吳友強 2015/4/30 Leaf 葉片 X-section 橫切面 : Palisade mesophyll 柵狀葉肉 Chloroplast 葉綠體 Quick Revision : Where does photosynthesis.

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Presentation on theme: "2015/4/30 Photosynthesis 光合作用 香港道教聯合會青松中學 吳友強 2015/4/30 Leaf 葉片 X-section 橫切面 : Palisade mesophyll 柵狀葉肉 Chloroplast 葉綠體 Quick Revision : Where does photosynthesis."— Presentation transcript:

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2 2015/4/30 Photosynthesis 光合作用 香港道教聯合會青松中學 吳友強

3 2015/4/30 Leaf 葉片 X-section 橫切面 : Palisade mesophyll 柵狀葉肉 Chloroplast 葉綠體 Quick Revision : Where does photosynthesis occur ? 電子顯微鏡下的葉綠體 Chloroplast under electron microscope

4 2015/4/30 Warm-up Questions The following microphotograph is a transverse section of a A. stem. B. leaf. C. root.

5 2015/4/30 Sorry, you’ve got the wrong answer!!! Can you find cortex ( 皮層 ), which is very obvious in a cross-section of a stem ? Try again...

6 2015/4/30 Sorry, you’ve got the wrong answer!!! Are the vascular bundles( 維管束 ) concentrated in the centre of the section ? Try again...

7 2015/4/30 Congratulations!!! You’ve got the correct answer!!! Go to next question...

8 2015/4/30 Warm-up Questions Here is a transverse section of a leaf. It is a leaf of A. monocotyledonous xerophyte B. dicotyledonous hydrophyte C. dicotyledonous mesophyte

9 2015/4/30 Sorry, you’ve got the wrong answer!!! Xerophyte is a kind of plants adapted in desert habitat. Try again...

10 2015/4/30 Sorry, you’ve got the wrong answer!!! Hydrophyte is a kind of plants adapted in aquatic habitat. Try again...

11 2015/4/30 Congratulations!!! You’ve got the correct answer!!! Bonus …….

12 2015/4/30 Bonus : Give two reasons to support your answer. Hints ??? ??? ???

13 2015/4/30 Definition of Photosynthesis Photosynthesis is a process by which green plants use sunlight trapped by chlorophyll to produce organic compounds (carbodyrate) from carbon dioxide and water, oxygen is released as by-product.

14 2015/4/30 Summary of Photosynthesis Carbon dioxide 二氧化碳 Water 水 Oxygen 氧 Glucose 葡萄糖 Chlorophyll 葉綠素 Sunlight 陽光

15 2015/4/30 Experiments : 1.To show that starch is produced during Photosynthesis. light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll

16 2015/4/30 Four steps : 1.Boil the leaf in water, why ? 2.Boil the leaf in alcohol, why ? 3.Wash the leaf in warm water, why ? 4.Add iodine solution to the leaf, what is the expected result ?

17 2015/4/30 Experiments : Aim : To show that light is necessary for Photosynthesis. Control : Do we need a Control for this experiment ? light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll

18 2015/4/30 Experiments : Aim : To show that chlorophyll is necessary for photosynthesis. light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll Control : Do we need a Control for this experiment ? Any Assumption ?

19 2015/4/30 Experiments : Aim : To show that carbon dioxide is necessary for photosynthesis. light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll Any Criticism on the set-up ? (Think about Variables.)

20 2015/4/30 Is it better ? light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll

21 2015/4/30 Experiments : Aim : To show that oxygen is produced during photosynthesis. light 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 chlorophyll

22 2015/4/30 Logics In an experiment, think about : Aim and objective Control experiment Dependent variables Independent variables Assumptions Limitations

23 2015/4/30 Limitations of the summary equation : 1.Photosynthesis is a two phase process, which cannot be shown in the equation. 2.Source of oxygen cannot be shown. 3.Glucose is not the first product of photosynthesis. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 light chlorophyll

24 2015/4/30 Photosynthesis involves two stages : Light reaction light is necessary light split water into hydrogen and oxygen Dark reaction light is not necessary hydrogen is used to reduce carbon dioxide to carbodyrate

25 2015/4/30 Water 水 Light 陽光 Chlorophyll 葉綠素 Oxygen 氧 Hydrogen 氫 (原子) Released from the plant Dark reaction Light reaction

26 2015/4/30 Hydrogen 氫 (原子) Carbon dioxide 二氧化碳 Carbohydrate 碳水化合物 Dark reaction

27 2015/4/30 This powerpoint was kindly donated to is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.


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