Chapter 8 Photosynthesis

Ch. 8-1 Energy & Life All living things need energy Plants capture energy from sunlight to produce food (autotrophs) Animals get energy from food (heterotrophs)

Chemical Energy One of the most imp. compounds that living things use to store energy – ATP ATP – adenosine triphosphate Has 3 parts: → When the bond is broken b/t the 2nd & 3rd phosphate energy is released

ATP – ADP cycle When ATP gives up some energy, it’s converted to ADP (adenosine diphosphate) ADP doesn’t have much energy, so it must be re-converted to ATP again

Ch. 8-2 Investigating Photosynthesis Van Helmont – discovered that plants gain most of their mass from water

Investigating Photo Priestly – discovered oxygen ←his expt. Ingenhousz – showed that plants give off O2 only when exposed to light

Equation for Photosynthesis 6 CO2 + 6 H2O → C6 H12 O6 + 6 O2 carbon dioxide + water → glucose + oxygen

Light & Photo Plants gather sunlight with light-absorbing molecules called pigments *necessary for photosynthesis! Main pigment is chlorophyll Chlorophyll absorbs light only in certain parts of the visible spectrum Two types of Chlorophyll: Chlorophyll a - absorbs blue-violet and red light. Chlorophyll b - absorbs blue and red light. Green light is not absorbed! It’s reflected!

Light & Photo Plants do not absorb light well in the green part of the spectrum. Why? (green light is reflected by plants, which is why they appear green) A pigment will be the color of the spectrum of light that it CANNOT absorb! http://www.sciencelearn.org.nz/Science-Stories/Harnessing-the-Sun/Sci-Media/Animations-and-Interactives/The-electromagnetic-spectrum

Accessory Pigments: Their purpose is to absorb light where chlorophyll does not – they absorb green light! (They complete the absorption spectrum) Carotenoids: which produce orange, red, and brown colors in such things as carrots, cranberries, grapes, and rutabagas Anthocyanins: produce purple, blue and red colors, such as: concord grapes, blueberries, and plums. Xanthophylls: produce yellow colors, such as in corn and daffodils

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Ch. 8-3 The Reactions of Photo Take place in the chloroplasts Parts of a chloroplast: thylakoids: sac- like photosynthetic membranes granum(a) – stacks of thylakoids stroma – space outside thylakoid http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/ great review video

Steps of Photosynthesis Two main parts: 1. Light-dependent reaction 2. Light-independent reaction (Calvin Cycle) 6 CO2 + 6 H2O → C6 H12 O6 + 6 O2 (2) (1) (2) (1) Electron Carriers When light excites electrons (e-) in chlorophyll, they gain energy These high-energy e- require a special carrier NADP+ is one e- carrier It is like an uncharged battery (like ADP) It turns to NADPH when charged http://www.mhhe.com/biosci/bio_animations/02_MH_Photosynthesis_Web/

Light-Dependent Reaction Take place in the grana / thylakoid membrane (with chlorophyll) Raw materials: light, water, ADP & NADP+ (uncharged batteries) Products: ATP, NADPH (charged & O2 (given off into air) Video Slower animation http://www.sumanasinc.com/webcontent/animations/content/harvestinglight.html http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html

Step 2 – Light Independent Reaction (Calvin Cycle) Raw materials: ATP, NADPH & CO2 Products: C6H12O6 Takes place in the stroma

Calvin Cycle – add to picture Uses ATP and NADPH from the light reactions to produce high-energy sugars such as glucose. Uses 6 molecules of CO2 to produce one 6-Carbon sugar. The sugar is either then used for immediate energy or to build larger molecules such as cellulose or starch.

Calvin cycle video clip http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html Calvin cycle animation http://faculty.nl.edu/jste/calvin_cycle.htm

Overview of Photosynthesis

Factors Affecting Photosynthesis a. Amount of water b. Temperature (photo depends on enzymes that work best at 0°C to 35°C (32oF to 95oF) c. Light Intensity d. CO2 concentration e. surface area of leaves

Factors Affecting Photo

Photosynthesis Review Round 1 Number your paper 1-8. 1. Name the energy storage molecule (the charged battery)._______ 2. What are organisms called that can produce their own food?_______ 3. What molecule can be compared to a partially charged battery?________ 4. Name the ultimate source of energy for plants & animals._____ 5. What are organisms called that get energy from other animals & plants? ________ What is the location of the high energy bond in ATP? _________ What is the simple sugar that stores great amounts of energy? ________ The 3 parts of ATP are: ________, _________ & 3 _________.

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Answers – Round 1 1. ATP 2. Autotroph 3. ADP 4. The sun 5. Heterotrophs 6. Between the 2nd & 3rd phosphate 7. Glucose 8. Adenine, ribose, 3 phosphates

Photosynthesis Review Round 2 Number your paper 1-4 Match each scientist with their contribution to photosynthesis: Plants gain most of their mass through water. Using a candle & a jar, he observed that plants produce a gas that kept the candle burning. Found that plants need sunlight to produce oxygen. Traced the path in plants that produces glucose; known as the light-independent reaction. Priestly Ingenhousz van Helmont Calvin

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Answers – Round 2 1. van Helmont 2. Priestly 3. Ingenhousz 4. Calvin

Photosynthesis Review Round 3 Number your paper 1-9. 1. Write the equation for photosynthesis in symbols. 2. Write the equation for photosynthesis in words. 3. Plants gather light with molecules called _______; the main one in plants is ____________. 4. Two areas of the visible spectrum that chlorophyll absorbs light well from are ______ & ______. 5. Photosynthesis occurs in the _________ of plants. 6. Photosynthetic membranes in the chloroplasts are called ___________. 7. A ______ is a stack of thylakoids. 8. The _________ is the space outside the grana. 9. _______ can be compared to a device used to transfer hot coals.

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Answers – Round 3 1. 6CO2 + 6H2O + light → C6H`2O6 + 6O2 2. carbon dioxide + water + light → glucose + oxygen 3. pigment; chlorophyll 4. blue & red 5. chloroplasts 6. thylakoids 7. granum 8. stroma 9. NAPD+

Photosynthesis Review Round 4 Number your paper 1-9. 1. The part of photosynthesis that requires light is called the _____________ reaction. 2. The part of photosynthesis that does not require light is called the _______ cycle. 3. Name 4 raw materials of the light- dependent reaction: ______, ______, ______ & ______. 4. Name 3 products of the light-dependent reaction: ______, ______ & ______. Name 3 raw materials of the Calvin cycle: _____, ______ & ________ Name 1 product of the Calvin cycle: ________. The light-dependent reaction takes place in the _______. The Calvin cycle takes place in the ________. Name 3 factors that affect the rate of photosynthesis:

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Answers – Round 4 light-dependent Calvin cycle (light-independent) Light, water, ADP & NADP+ ATP, NADPH, & O2 ATP, NADPH & CO2 C6H12O6 (glucose) grana stroma 9. temperature, light & water

Photosynthesis Review Round 5 Number your paper 1-8. Multiple Choice: Which of the following is an autotroph: A. cheetah B. mushroom C. fern D. frog One of the most important compounds that living things use to store energy is: A. DNA B. ATP C. H2O D. CO2 Which scientist discovered oxygen? A. Van Helmont B. Calvin C. Priestly D. Ingenhousz The products of photosynthesis are: A. sugar & oxygen B. water & CO2 C. oxygen & hydrogen D. sugar & carbon dioxide

Photosynthesis Review Round 5 Which substance from the light-dependent reaction of photosynthesis is a source of energy for the Calvin cycle? A. ADP B. H2O C. NADPH D. CO2 In which structures in a chloroplast does the Calvin cycle take place? A. stroma B. grana C. thylakoid D. stacks of pancakes The leaves of a plant appear green because chlorophyll: A. reflects blue light B. absorbs blue light C. reflects green light D. absorbs green light Which molecule stores the most amount of energy? A. ADP B. ATP C. fat D. glucose

Answers – Round 5 1. C 2. B 3. C 4. A 5. C 6. A 7. C 8. D

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