Integrated Science M1 Photosynthesis Process

OBJECTIVESOBJECTIVESWhere does

photosynthesis occur?

Where does photosynthesis

occur?

The chemical processes


Photochemical reactions


REVIEW ACTIVITIESREVIEW

ACTIVITIESINTRODUCTIONINTRODUCTION

THE PHOTOSYNTHESIS PROCESSTHE PHOTOSYNTHESIS PROCESS

Integrated Science Module 1 Unit 2 Lesson 4

Integrated Science Module 1 Unit 2 Lesson 4

BEGIBEGINNPhoto from: http://schools.utah.gov/arc/curr/grade8scienceoer.pdf




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INTRODUCTIONINTRODUCTION

In this lesson, you will look more closely at a special photochemical process that goes on inside green plant parts, such as leaves, as they carry on photosynthesis.

You will also briefly look at other photochemical processes that can occur around us.

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OBJECTIVESOBJECTIVES

When you complete this slide presentation, you will be able to: relate the leaf structure to its function in photosynthesis.state the importance of magnesium ions for photosynthesis.briefly describe the chemical reactions of the ‘light’ and ‘dark’ phases of photosynthesis.define a photochemical reaction and give at least two examples.access and discuss information from the internet.

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Where does photosynthesis occur? Where does photosynthesis occur?

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In flowering plants, green leaves are the main places main places where photosynthesis occurs. Leaves are arranged onthe stem to expose them tothe maximum amount of sunlight.Photosynthesis can also occur in green stems of a plant.

Read pages 1 – 2 at > http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/green_world/leavesrev1.shtml

http://en.wikipedia.org/wiki/Leaf http://www.encyclopedia.com/topic/stem.aspx

http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/green_world/leavesrev1.shtml

http://www.encyclopedia.com/topic/stem.aspx

http://upload.wikimedia.org/wikipedia/commons/d/d8/Leaves_opposite.jpg

http://en.wikipedia.org/wiki/Image:Stem_nodes.jpg




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Watch > http://www.youtube. com/watch?v=co0JdqUlycg

Point on the labels for definitions.

Watch > http://www.youtube. com/watch?v=co0JdqUlycg

Point on the labels for definitions.

Cuticle

Upper Epidermis

Air space

Guard cell at Stoma

Lower Epidermis

Spongy mesophyll cells

Phloem in a vein

Xylem and

Palisade mesophyll cells

Where does photosynthesis occur?

http://www.youtube.com/watch?v=co0JdqUlycg

http://www.youtube.com/watch?v=co0JdqUlycg




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Where does photosynthesis occur?Where does photosynthesis occur?Structure and Function of stomataStructure and Function of stomata

Stomata, surrounded by their guard cells, are abundant on the lower epidermis. CO2 (& also O2) pass in/out each stoma.

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Watch this next video up to 2.45 min > http://www.youtube.com/watch?v=IlmgFYmbAUg&NR=1&feature=endscreen

Watch this next video up to 2.45 min > http://www.youtube.com/watch?v=IlmgFYmbAUg&NR=1&feature=endscreen

http://www.ck12.org/biology/Photosynthesis/lesson/user%3Asschultz/Photosynthesis/#x-ck12-QmlvLTE2LTEyLWxlYWYtc3RydWN0dXJlcw

http://www.youtube.com/watch?v=IlmgFYmbAUg&NR=1&feature=endscreen

http://www.youtube.com/watch?v=IlmgFYmbAUg&NR=1&feature=endscreen




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The actual site of photosynthesisThe actual site of photosynthesis

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http://www.skinnerscience.com/Biology/gcse%20unit2%20revision%20notes.htm

Mesophyll leaf cells contain chloroplasts, in which is chlorophyll, a light-absorbing pigment. Click, watch and listen > http://www.youtube.com/watch?v=OF_F9cAvLlQ&feature=relatedSo, chloroplasts, inside leaf/stem cells, are the sites of photosynthesis!

Palisade mesophyll cell with chloroplasts

http://www.skinnerscience.com/Biology/gcse%20unit2%20revision%20notes.htm

http://www.youtube.com/watch?v=OF_F9cAvLlQ&feature=related




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Where does photosynthesis occur?Where does photosynthesis occur?The importance of Chlorophyll The importance of Chlorophyll

The chlorophyll molecule has a central metal ion, Magnesium.. Plants need magnesium ions to make chlorophyll. If there is no chlorophyll, some reactions of photosynthesis cannot occur!

Formula of Chlorophyll = C55H72O5N4MgChlorophyll is found in the folded stacks of membranes in chloroplasts where some reactions of photosynthesis occur. Watch > http://www.nbclearn.com/chemistrynow/week9

http://www.nbclearn.com/chemistrynow/week9




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Summary of ‘typical’ leaf adaptations for Summary of ‘typical’ leaf adaptations for photosynthesisphotosynthesis

Arrangement of leaves on the stem exposes each leaf to the maximum amount of sunlight.

Usually broad leaf blade (lamina) that provides a large surface area to capture as much sunlight as possible.

Flat, thin leaf blade to allow gaseous exchange to occur quickly between air and mesophyll cells, via stomata.

Veins to keep the leaf surface flat and to transport H2O to mesophyll cells and translocate sugars for storage elsewhere.

Transparent waxy cuticle to reduce H2O loss from epidermis. Presence of chlorophyll in mesophyll cells to trap sunlight

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The Chemical ProcessesThe Chemical Processes

Photosynthesis involves two sets of chemical reactions or processes:

1. Light–dependent reactions which is a photochemical process (that means it MUST have light!!) is the first stage.

2. Light-independent or “dark” reactions.NOTE: The dark reactions can and do occur in the presence of light.Click, watch and listen to >http://www.goldiesroom.org/Multimedia/Movie_Clips/05%20Nutrition/Photosynthesis%20Review.wmv

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http://www.goldiesroom.org/Multimedia/Movie_Clips/05%20Nutrition/Photosynthesis%20Review.wmv

http://www.goldiesroom.org/Multimedia/Movie_Clips/05%20Nutrition/Photosynthesis%20Review.wmv




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The Chemical Processes: The Chemical Processes: Light-dependent Light-dependent reactionsreactions

1. The Light-dependent reactions refer to the “photo” part of photosynthesis.

They occur on the folded stacks of membranes inside chloroplasts, where light is absorbed by chlorophyll. The products (ATP, H+ ions and OH- ions) require further processing, so this occurs during the "dark" reactions. cont’d

11http://www.dnr.sc.gov/ael/personals/pjpb/lecture/chloroplast_structure.gif

http://www.dnr.sc.gov/ael/personals/pjpb/lecture/chloroplast_structure.gif




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Briefly, this is what happens: In the light-dependent reactions, CO2 and H2O are

substrates/reactants. Radiant energy is absorbed by chlorophyll, which is activated and converts light energy into chemical energy

and forms high-energy storage molecules (*ATP & NADPH) for use later.

[*Adenosine Tri-Phosphate]

cont’d

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The Chemical Processes: The Chemical Processes: Light-dependent Light-dependent reactionsreactions




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The Chemical Processes: The Chemical Processes: Light-dependent Light-dependent reactions reactions

The energy of (sun)light is used to split H2O into hydrogen ions and hydroxyl ions as shown:

H2O ------------- (H)+ and (OH)- Chlorophyll

O2 gas is formed from reactions, involving hydroxyl ions, as a by-product (and it can be used in cellular respiration!).

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light

http://www.elateafrica.org/elate/biology/nutrition/mechanismofphotosynthesis.html




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The Chemical Processes: The Chemical Processes: Light-independ-Light-independ-ent reactions or Calvin cycle ent reactions or Calvin cycle

2. The “dark” or light-independent reactions are the “synthesis” part of photosynthesis that just need the products of the light reactions.

These reactions occur in the stroma of chloroplasts. High-energy molecules (ATP, NADPH) created earlier,

‘power’ this phase of photosynthesis. The hydrogen ions and chemical energy that were

produced during the light dependent phase are used to reduce CO2 to form simple sugars e.g. glucose.

Chemical energy is stored in the bonds that join elements to form sugars such as glucose.

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The Chemical ProcessesThe Chemical ProcessesFood products from photosynthesisFood products from photosynthesis

From simple sugars formed in photosynthesis: Plants make other organic molecules, e.g. sugar molecules form complex carbohydrates such as

cellulose and insoluble starch. amino acids which join together to build various plant

proteins, enzymes, etc. fatty acids and lipids. Plants may store sugars, starch, fats, proteins.Sugars are used in respiration to release energy.

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The Chemical Processes - The Chemical Processes - SummarySummary

1. To see a summary of the chemical processes, scroll down and examine the flow diagram at: http://www.angelfire.com/sc2/rvcscience/photosynthesisFlowChart.html

2. Explain in four steps what it is showing. Tell your teacher if s/he calls on you. Listen as others explain! Make notes in the box below.

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FEEDBACKFEEDBACK

http://www.angelfire.com/sc2/rvcscience/photosynthesisFlowChart.html




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The Chemical Processes – The Chemical Processes – Summary Summary Feedback Feedback

1. Examine the flow diagram and explain in four steps what it is showing.

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FEEDBACK Chlorophyll in chloroplasts capture energy from sunlight.Chlorophyll in chloroplasts capture energy from sunlight.

Energy is used to split water, releasing O2 and is also carried to the stroma.

Energy is used to split water, releasing O2 and is also carried to the stroma.

Hydrogen and the CO2 taken in are both carried to the stroma, where they combine to make carbohydrate.

Hydrogen and the CO2 taken in are both carried to the stroma, where they combine to make carbohydrate.

Carbohydrate carried to plant cells.Carbohydrate carried to plant cells.

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2

3

4

Show me




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The Chemical Processes – The Chemical Processes – Photochemical reactionsPhotochemical reactions

2. The song played for that flow diagram is “Here comes the sun”. Why do you think that song was chosen?

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2.The song ‘Here comes the sun’ was chosen because (sun)light is important for those chemical reactions of photosynthesis. NOTE: Any chemical reaction that uses, or is influenced by the presence of, light energy, is said to be a photochemical photochemical processprocess.

FEEDBACK TO QUESTION 2FEEDBACK TO QUESTION 2




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SUMMARYSUMMARY

1. Check > http://studyjams.scholastic.com/studyjams/jams/science/plants/photosynthesis.htmhttp://www.ck12.org/biology/Photosynthesis/lesson/user%3Asschultz/Photosynthesis/#x-ck12-QmlvLTE2LTEyLWxlYWYtc3RydWN0dXJlcw..“Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar.” http://en.wikipedia.org/wiki/Photosynthesis

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http://studyjams.scholastic.com/studyjams/jams/science/plants/photosynthesis.htm

http://www.ck12.org/biology/Photosynthesis/lesson/user%3Asschultz/Photosynthesis/




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Photochemical reactionsPhotochemical reactions

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2HBr hν H2 + Br2

Cl2 + H2 2HCl [no reaction in darkness]

Photosynthesis: e.g. in plants - a photochemical reaction in which simple molecules form a larger organic molecule.

There are other types of photochemical reactions: Photodissociation e.g. Photolysis of hydrogen bromide.

Example - Formation of hydrogen chloride:

6CO2

Carbon dioxide

6H2O

Water

C6H12O6

Sugar

6O2

Oxygen

++Light




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Photochemical reactions Photochemical reactions Main steps in Main steps in Photography Photography

Photography – very briefly …

1.A photographic film has a coating of light-sensitive silver salts on its surface, whose granules are activated when exposed to light.

2.Development: Treating the exposed film with a reducing agent accelerates the reduction of the activated granules to metallic silver (black).

3.A negative results, as shown on the next slide.

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AgBr AgBr*hν




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Photochemical reactionsPhotochemical reactionsMain steps in Main steps in PhotographyPhotography

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Just as how glucose then starch and O2 are the final products of photosynthesis, the final products of the photographic photochemical reactions are a negative (Left) in which light areas are dark and vice versa, then a positive or print of the object, (Right).




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Photochemical reactionsPhotochemical reactionsFirefliesFireflies

Bioluminescence ‘In fireflies, an enzyme in the abdomen catalyzes a reaction that results in bioluminescence.’In Jamaica, we call these insects “peenie wallies” . They carry out such photochemical reactions that enable them to flash light.

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http://www.facebook.com/people/Peenie-Wallie/100002164643523

http://en.wikipedia.org/wiki/Fireflies

http://en.wikipedia.org/wiki/Bioluminescence

http://www.facebook.com/people/Peenie-Wallie/100002164643523




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Humans rely on photochemical reactions for the formation of vitamin D in our skin when it is exposed to sunlight.

Our vision is initiated by a photochemical reaction. When light contacts the two types of sensory cells in our eyes, a series of complex chemical reactions occur. The chemical that is formed creates electrical impulses in the optic nerve which travel to the brain for interpretation.

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http://en.wikipedia.org/wiki/Photochemistryhttp://science.howstuffworks.com/life/human-biology/eye2.htm




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Photochemical reactionsPhotochemical reactionsTanningTanning

Tanning and sun burning are the result of photochemical reactions in our skin, caused by ultraviolet light that reach the Earth.

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http://www.open.edu/openlearn/nature-environment/natural-history/rough-science-carriacou-make-sunblock-challenge

http://en.wikipedia.org/wiki/File:Sunburn.jpg

http://en.wikipedia.org/wiki/File:Sunburn.jpg




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Photodegradation occurs in many materials e.g. PVC materials.

In many cases, ‘medicine bottles are made with darkened glass’ to prevent photodegradation of drugs they contain.

Look at samples of new and old paper; the yellowing seen in the old paper is an example of photochemical reactions having taken place.

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http://en.wikipedia.org/wiki/Photochemistry




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Quick QuizQuick Quiz

Are you ready for a Quick Quiz?Choose a partner. Take turns to ask each other alternate questions. Write your answer then have the questioner give feedback. Use questions at the following websites:http://www.neok12.com/diagram/Photosynthesis-01.htmhttp://www.neok12.com/quiz/PHOSYN02http://www.neok12.com/quiz/PHOSYN03http://www.biotopics.co.uk/plants/leafst.html

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http://www.neok12.com/diagram/Photosynthesis-01.htm

http://www.neok12.com/quiz/PHOSYN02

http://www.neok12.com/quiz/PHOSYN03

http://www.biotopics.co.uk/plants/leafst.html




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M.C. Question 1M.C. Question 1

The Carbon incorporated into the carbohydrate formed in photosynthesis comes from

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B. glucose

D. chlorophyll

C. water that is absorbed

A. carbon dioxide

FEEDBACKFEEDBACKFEEDBACKFEEDBACK




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Feedback to M. C. Question 1 Feedback to M. C. Question 1

The Carbon incorporated into the carbohydrate formed in photosynthesis comes from Carbon dioxide.

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The answer is A. Carbon dioxide is correct.

During the dark or light-independent reactions of photosynthesis, Carbon dioxide undergoes what is called reduction reactions (see slide 27) from which CO combines with H2O to give an organic molecule CH2O which is built up into glucose.

NEXT QUESTIONNEXT QUESTIONNEXT QUESTIONNEXT QUESTION




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M.C. Question 2M.C. Question 2

Which tissue in a ‘dicot’ leaf represents the main site of photosynthesis?

A. Lower epidermis

D. Spongy mesophyll

C. Upper epidermis

B. Palisade mesophyll





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Feedback to M.C. Question 2Feedback to M.C. Question 2

Which tissue in a ‘dicot’ leaf represents the main site of photosynthesis?

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The answer is ‘B’ and not ‘D’ because palisade mesophyll cells have more chloroplasts per cell than spongy mesophyll cells.

Look again at slide 5 to see their location in the leaf.




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Review Question 1Review Question 1

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Look at the diagrams of tomato plants. The one on the right has been deprived of nutrient ions, especially magnesium. What do you observe has happened to the plant deprived of magnesium? Tell your teacher what you think.

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/plants/plants3.shtml





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Feedback to Review Question 1 Feedback to Review Question 1

What do you observe has happened to the plant deprived of magnesium?

Plants deprived of magnesium will not be able to make chlorophyll. Because no chlorophyll is being made in any cell, the plant cannot trap light energy and use it in the reactions of photosynthesis to make the food and other substances, containing stored chemical energy, that it needs to carry on various life processes. So, its leaves turn yellow; it shows stunted growth, cannot stay upright and soon dies!




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1. Why is light necessary for photosynthesis?

2. What does photosynthesis and solar panels have in common?

3. Why is chlorophyll necessary for photosynthesis?

4. What is the role of water in photosynthesis?

5. What is the role of Carbon dioxide in photosynthesis?

Questions 6-8 continue on the next slide.

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Type your responses in the box. You need to be in Slide Show view to type and delete text.




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6. Why are photography and the yellowing of paper when left out in the sunlight considered to involve photochemical reactions?

7. Why are human beings and other organisms not able to carry out the energy transformation that occurs in photosynthesis?

8. What is the ‘aim’ of plants in photosynthesis?”

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Type your responses in the box. You need to be in Slide Show view to type and delete text.





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Feedback to Quick QuizFeedback to Quick Quiz

1. Light provides energy to split H2O and form high-energy molecules.2. Both green leaves and solar panels need a lot of light energy for their

photochemical reactions.3. Chlorophyll traps the radiant energy of the sun and makes it available for the

photochemical reactions.4. Water supplies the hydrogen atoms needed to form sugar. 5. CO2 supplies the C and O atoms to combine with H to form sugars.6. Both involve chemical reactions that are initiated by exposure to light. 7. Because plant cells have chloroplasts with pigments such as chlorophyll that are

able to trap radiant energy from the sun. The cells of humans and other organisms lack this organelle and pigment.

8. To carry out nutrition by trapping radiant energy, converting it into chemical energy and storing it within food molecules for their own use in growth and metabolism.

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HOMEWORK ACTIVITYHOMEWORK ACTIVITY

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Your Science Club is organizing an open day. You have been chosen to explain the process of photosynthesis. This is the chart that your group has prepared. Use it to write a one-page summary of your speech on photosynthesis. Hand it in for marking.

Check your facts at > http://www.redorbit.com/news/video/education_1/1112728981/what-is-photosynthesis/

Your Science Club is organizing an open day. You have been chosen to explain the process of photosynthesis. This is the chart that your group has prepared. Use it to write a one-page summary of your speech on photosynthesis. Hand it in for marking.

Check your facts at > http://www.redorbit.com/news/video/education_1/1112728981/what-is-photosynthesis/

http://www.redorbit.com/news/video/education_1/1112728981/what-is-photosynthesis/

http://www.redorbit.com/news/video/education_1/1112728981/what-is-photosynthesis/




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End of ActivityEnd of Activity

You have reached the end of the activity. If you wish to review any of the concepts in this lesson, go

to the first slide and click on the Menu. If you have finished viewing these slides, click the Close

(X) button.

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CREDITSCREDITS

• http://www.fotosearch.com/photos-images/green-leaves.html http://www.cfkeep.org/uploads/photosynthesis.ppt#256,1,Photosynthesis http://www.fotosearch.com/photos-images/green-leaves.html http://pecsgroup5.free.fr/blabla/1ST%20SEMESTER/Chemistry/Lectures/General

%20chemistry/Photochemistry.ppt.http://faculty.sgc.edu/asafer/BIOL1107/chapt08_lecture.ppt.http://science.howstuffworks.com/life/human-biology/eye2.htm

http://en.wikipedia.org/wiki/Photosynthesis “Alapertelmezett terv” http://www.facebook.com/people/Peenie-Wallie/100002164643523 http://en.wikipedia.org/wiki/File:Sunburn.jpg http://www.open.edu/openlearn/nature-environment/natural-history/rough-science-

carriacou-make-sunblock-challenge http://en.wikipedia.org/wiki/Photochemistry http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/plants/plants3.shtm

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Education

Integrated Science M1 Photosynthesis Process