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5.2 Notes…continued Analyze the function of electron transport chains in the second stage of photosynthesis. Relate the Calvin cycle to carbon dioxide fixation in the third stage of photosynthesis. Identify three environmental factors that affect the rate of photosynthesis.
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Stage Two: Conversion of Light Energy
The absorbed light energy in electrons is used to make three different products… __________ Since these substances need light to be produced, stage two is referred to as the ____________ _________________ reactions ATP O2 NADPH light dependent
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As electrons move down the molecules, they release ____________…
Section 2 Photosynthesis First an excited electron _______ to a nearby molecule in the thylakoid membrane. Then the electron is passed down a series of molecules along the membrane called an _____________ _______________ ____________ (ETC) As electrons move down the molecules, they release ____________… Similar to how a bucket brigade loses water jumps chain electron transport energy
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Electron Transport Chains of Photosynthesis
Chapter 5 Section 2 Photosynthesis Electron Transport Chains of Photosynthesis
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Chapter 5 Section 2 Photosynthesis The first electron transport chain lies between the two green ___________ of pigment molecules clusters The first pigment cluster is called _________________ (PSII) because it was the second one discovered It absorbs energy and releases an excited ____________ Photosystem II electron
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Chapter 5 Section 2 Photosynthesis The excited electron jumps to the next molecule in the electron transport chain, releasing ____________ energy This energy is used by a membrane pump that pumps ___________________ ions _______ the thylakoid into hydrogen
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Chapter 5 Section 2 Photosynthesis This creates a __________ ____ of hydrogen ions inside the thylakoid build up This concentration gradient causes hydrogen ions to ________________ through a transport protein _____ of the thylakoid into the ___________ out diffuse stroma
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Chapter 5 Section 2 Photosynthesis The flow of hydrogen ions causes the transport protein to __________ spin force The spinning action creates a __________ that binds a phosphate group to ADP, producing _______ Since this transport protein produces ATP, it is called _____________________ ATP ATP synthetase / ATP Synthase
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Chapter 5 Section 2 Photosynthesis The energy released from the electrons also allows an enzyme to split a ______ molecule into hydrogen atoms and the gas ___ water O2 Chlorophyll molecules replace their excited electrons by taking an electron from hydrogen atoms, leaving them as _______. This allows light energy to excite ___________ electron in PSII ions another
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Chapter 5 Section 2 Photosynthesis The second cluster of pigments is called ______________ (PSI) because it was the first one discovered Photosystem I The original excited electron from ______ is eventually passed to PSI, where chlorophyll molecules will absorb light energy and __________ the electron again PSII excite
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Chapter 5 Section 2 Photosynthesis These excited electrons move down a ________ electron transport chain, releasing energy second hydrogen The released energy is used to bind a ___________ ion to NADP+, which forms ___________ NADPH
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Chapter 5 Section 2 Photosynthesis NADPH is an electron ___________ that provides the high-energy electrons needed to make ___________ in the third stage of photosynthesis Review… What three products are made during the light-dependent reactions? carrier sugar ATP O2 NADPH
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Stage Three: Formation of Organic Compounds
Chapter 5 Section 2 Photosynthesis Stage Three: Formation of Organic Compounds In the third (final) stage of photosynthesis, carbon atoms from _________________ in the atmosphere are used to make organic compounds, such as ______________, in which chemical energy is stored. The transfer of carbon dioxide to organic compounds is called carbon dioxide _______________ These reactions do not require light energy, so stage three is referred to as the light ____________________or _____ reactions carbon dioxide glucose fixation independent dark
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Chapter 5 Section 2 Photosynthesis Sugars are formed in the _______________________, which is named after __________ __________, the scientist who discovered it ***Occurs in the ____________ Calvin cycle Melvin Calvin stroma
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Chapter 5 Section 2 Photosynthesis First ____ CO2 molecules are added to ____ 5-carbon compounds called ____________ ____________ (_______) 3 3 ribulose biphosphate RuBP
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Chapter 5 Section 2 Photosynthesis These form 3 unstable ___-carbon compounds that immediately split into ____ 3-carbon compounds called ____________ ____________ 6 6 phosphoglyceric acid (PGA)
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Chapter 5 Section 2 Photosynthesis Next, the ATP and NADPH made during the _________ reactions supply _______ for ___ 3-carbon sugars, called ____________ ___________, to be made light energy 6 phosphoglycer- aldehyde (PGAL)
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Chapter 5 Section 2 Photosynthesis One PGAL is used by the plant to synthesize ___________,while the others regenerate RuBP, which began the cycle sugars
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Chapter 5 Section 2 Photosynthesis As shown in the diagram, RuBP needs another phosphate before the cycle can begin again… where does it come from? ATP
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Chapter 5 glucose C6H12O6 6 Section 2 Photosynthesis
What organic compound does a plant need to make for itself? What is its formula? How many carbon atoms does it contain? glucose C6H12O6 6
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Chapter 5 Section 2 Photosynthesis How many carbons are in the initial sugar produced? So while this diagram shows 3 CO2 molecules, photosynthesis really needs _____ 3 6
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Fill in the coefficients in the equation for photosynthesis below…
light 6 6 6 __ CO __ H > C6H __ O2
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Chapter 5 Section 2 Photosynthesis Photosynthesis is directly affected by various environmental factors such as… _____________________ The rate of photosynthesis will increase with light intensity and CO2 concentration, until all of the _____________ are being used or the _________ cycle cannot process CO2 any faster Because photosynthesis involves ___________, it is most ___________ within a specific temperature range Light intensity CO2 concentration temperature pigments Calvin enzymes efficient
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Question 1 In what part of the chloroplast are the electron transport chains located? In the thylakoid membranes
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Question 2 Which of the following is not a product of the light-dependent reactions? A. O2 B. glucose C. ATP D. NADPH
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Question 3 Which molecule is necessary to start the Calvin cycle?
A. O2 B. glucose C. CO2 D. ADP
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Question 4 What two other names are used to describe the Calvin cycle?
Light independent reactions Dark reactions
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