CAMPBELL BIOLOGY TENTH EDITION Reece Urry Cain Wasserman Minorsky Jackson 10 Photosynthesis Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick
The Process That Feeds the Biosphere Photosynthesis is the process that converts solar energy into chemical energy Directly or indirectly, photosynthesis nourishes almost the entire living world
Autotrophs sustain themselves without eating anything derived from other organisms Autotrophs are the producers of the biosphere, producing organic molecules from CO 2 and other inorganic molecules Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules
Figure 10.1
Figure 10.1a Other organisms also benefit from photosynthesis.
Photosynthesis occurs in plants, algae, certain other unicellular eukaryotes, and some prokaryotes These organisms feed not only themselves but also most of the living world
Figure 10.2 (a) Plants (d) Cyanobacteria 40 µm (b) Multicellular alga 1 µm (e) Purple sulfur bacteria 10 µm (c) Unicellular eukaryotes
Figure 10.2a (a) Plants
Figure 10.2b (b) Multicellular alga
Figure 10.2c 10 µm (c) Unicellular eukaryotes
Figure 10.2d (d) Cyanobacteria 40 µm
Figure 10.2e 1 µm (e) Purple sulfur bacteria
Heterotrophs obtain their organic material from other organisms Heterotrophs are the consumers of the biosphere Almost all heterotrophs, including humans, depend on photoautotrophs for food and O 2
Earth s supply of fossil fuels was formed from the remains of organisms that died hundreds of millions of years ago In a sense, fossil fuels represent stores of solar energy from the distant past
Figure 10.3
Concept 10.1: Photosynthesis converts light energy to the chemical energy of food Chloroplasts are structurally similar to and likely evolved from photosynthetic bacteria The structural organization of these organelles allows for the chemical reactions of photosynthesis
Chloroplasts: The Sites of Photosynthesis in Plants Leaves are the major locations of photosynthesis Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf Each mesophyll cell contains 30 40 chloroplasts CO 2 enters and O 2 exits the leaf through microscopic pores called stomata
A chloroplast has an envelope of two membranes surrounding a dense fluid called the stroma Thylakoids are connected sacs in the chloroplast which compose a third membrane system Thylakoids may be stacked in columns called grana Chlorophyll, the pigment which gives leaves their green colour, resides in the thylakoid membranes
Figure 10.4 Leaf cross section Chloroplasts Vein Mesophyll Stomata CO 2 O 2 Chloroplast Mesophyll cell Thylakoid Thylakoid Stroma Granum space Outer membrane Intermembrane space Inner membrane 20 µm 1 µm
Figure 10.4a Leaf cross section Chloroplasts Vein Mesophyll Stomata Chloroplast CO 2 O 2 Mesophyll cell 20 µm
Figure 10.4b Chloroplast Thylakoid Thylakoid Stroma Granum space Outer membrane Intermembrane space Inner membrane 1 µm
Figure 10.4c Stroma Granum 1 µm
Figure 10.4d Mesophyll cell 20 µm
Tracking Atoms Through Photosynthesis: Scientific Inquiry Photosynthesis is a complex series of reactions that can be summarized as the following equation: 6 CO 2 + 12 H 2 O + Light energy C 6 H 12 O 6 + 6 O 2 + 6 H 2 O The overall chemical change during photosynthesis is the reverse of the one that occurs during cellular respiration
The Splitting of Water Chloroplasts split H 2 O into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules and releasing oxygen as a by-product
Figure 10.5 Reactants: 6 CO 2 12 H 2 O Products: C 6 H 12 O 6 6 H 2 O 6 O 2
Photosynthesis as a Redox Process Photosynthesis reverses the direction of electron flow compared to respiration Photosynthesis is a redox process in which H 2 O is oxidized and CO 2 is reduced Photosynthesis is an endergonic process; the energy boost is provided by light
Figure 10.UN01 becomes reduced becomes oxidized
The Two Stages of Photosynthesis: A Preview Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part) The light reactions (in the thylakoids) Split H 2 O Release O 2 Reduce the electron acceptor NADP + to NADPH Generate ATP from ADP by photophosphorylation
The Calvin cycle (in the stroma) forms sugar from CO 2, using ATP and NADPH The Calvin cycle begins with carbon fixation, incorporating CO 2 into organic molecules
Figure 10.6-1 Light H 2 O NADP + LIGHT REACTIONS ADP + P i Thylakoid Stroma Chloroplast
Figure 10.6-2 Light H 2 O NADP + Thylakoid LIGHT REACTIONS ADP + P i ATP NADPH Stroma Chloroplast O 2
Figure 10.6-3 Light H 2 O CO 2 NADP + Thylakoid LIGHT REACTIONS ADP + P i ATP NADPH CALVIN CYCLE Stroma Chloroplast O 2
Figure 10.6-4 Light H 2 O CO 2 NADP + Thylakoid LIGHT REACTIONS ADP + P i ATP NADPH CALVIN CYCLE Stroma Chloroplast O 2 [CH 2 O] (sugar)
BioFlix: The Carbon Cycle
BioFlix: Photosynthesis
Concept 10.2: The light reactions convert solar energy to the chemical energy of ATP and NADPH Chloroplasts are solar-powered chemical factories Their thylakoids transform light energy into the chemical energy of ATP and NADPH
The Nature of Sunlight Light is a form of electromagnetic energy, also called electromagnetic radiation Like other electromagnetic energy, light travels in rhythmic waves Wavelength is the distance between crests of waves Wavelength determines the type of electromagnetic energy
The electromagnetic spectrum is the entire range of electromagnetic energy, or radiation Visible light consists of wavelengths (including those that drive photosynthesis) that produce colors we can see Light also behaves as though it consists of discrete particles, called photons
Figure 10.7 1 m 10 5 nm 10 3 nm 1 nm 10 3 nm 10 6 nm (10 9 nm) 10 3 m Gamma rays X-rays UV Infrared Microwaves Radio waves Visible light 380 450 500 550 600 650 700 750 nm Shorter wavelength Higher energy Longer wavelength Lower energy
Photosynthetic Pigments: The Light Receptors Pigments are substances that absorb visible light Different pigments absorb different wavelengths Wavelengths that are not absorbed are reflected or transmitted Leaves appear green because chlorophyll reflects and transmits green light
Figure 10.8 Light Reflected light Chloroplast Absorbed light Granum Transmitted light
Animation: Light and Pigments
A spectrophotometer measures a pigment s ability to absorb various wavelengths This machine sends light through pigments and measures the fraction of light transmitted at each wavelength
Figure 10.9 White light Refracting prism Chlorophyll solution 2 3 Photoelectric tube Galvanometer 1 4 Slit moves to pass light of selected wavelength. Green light The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green light. Blue light The low transmittance (high absorption) reading indicates that chlorophyll absorbs most blue light.
An absorption spectrum is a graph plotting a pigment s light absorption versus wavelength The absorption spectrum of chlorophyll a suggests that violet-blue and red light work best for photosynthesis An action spectrum profiles the relative effectiveness of different wavelengths of radiation in driving a process
Figure 10.10 Absorption of light by chloroplast pigments Chlorophyll a Chlorophyll b Carotenoids 400 500 600 700 Wavelength of light (nm) (a) Absorption spectra Rate of photosynthesis (measured by O 2 release) (b) Action spectrum 400 500 600 700 Aerobic bacteria Filament of alga 400 500 600 700 (c) Engelmann s experiment
Figure 10.10a Absorption of light by chloroplast pigments Chlorophyll a Chlorophyll b Carotenoids 400 500 600 700 Wavelength of light (nm) (a) Absorption spectra
Figure 10.10b Rate of photosynthesis (measured by O 2 release) (b) Action spectrum 400 500 600 700
Figure 10.10c Aerobic bacteria Filament of alga 400 500 600 700 (c) Engelmann s experiment
The action spectrum of photosynthesis was first demonstrated in 1883 by Theodor W. Engelmann In his experiment, he exposed different segments of a filamentous alga to different wavelengths Areas receiving wavelengths favorable to photosynthesis produced excess O 2 He used the growth of aerobic bacteria clustered along the alga as a measure of O 2 production
Chlorophyll a is the main photosynthetic pigment Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis The difference in the absorption spectrum between chlorophyll a and b is due to a slight structural difference between the pigment molecules Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll
Figure 10.11 CH 3 CH 3 CHO in chlorophyll a in chlorophyll b Porphyrin ring: light-absorbing head of molecule; note magnesium atom at center Hydrocarbon tail: interacts with hydrophobic regions of proteins inside thylakoid membranes of chloroplasts; H atoms not shown
Video: Space-Filling Model of Chlorophyll a
Accessory pigments called carotenoids function in photoprotection; they absorb excessive light that would damage chlorophyll
Excitation of Chlorophyll by Light When a pigment absorbs light, it goes from a ground state to an excited state, which is unstable When excited electrons fall back to the ground state, photons are given off, an afterglow called fluorescence If illuminated, an isolated solution of chlorophyll will fluoresce, giving off light and heat
Figure 10.12 e Excited state Energy of electron Photon Chlorophyll molecule Ground state Heat Photon (fluorescence) (a) Excitation of isolated chlorophyll molecule (b) Fluorescence
Figure 10.12a (b) Fluorescence
A Photosystem: A Reaction-Center Complex Associated with Light-Harvesting Complexes A photosystem consists of a reaction-center complex (a type of protein complex) surrounded by light-harvesting complexes The light-harvesting complexes (pigment molecules bound to proteins) transfer the energy of photons to the reaction center
Figure 10.13 Photosystem Photon Lightharvesting complexes Reactioncenter complex STROMA Primary electron acceptor Thylakoid membrane Transfer of energy e Special pair of chlorophyll a molecules THYLAKOID SPACE (INTERIOR OF THYLAKOID) (a) How a photosystem harvests light Pigment molecules Thylakoid membrane Protein subunits Chlorophyll (b) Structure of a photosystem STROMA THYLA- KOID SPACE
Figure 10.13a Photosystem Photon Lightharvesting complexes Reactioncenter complex STROMA Primary electron acceptor Thylakoid membrane Transfer of energy e Special pair of chlorophyll a molecules THYLAKOID SPACE (INTERIOR OF THYLAKOID) (a) How a photosystem harvests light Pigment molecules
Figure 10.13b Thylakoid membrane Protein subunits Chlorophyll (b) Structure of a photosystem STROMA THYLA- KOID SPACE
A primary electron acceptor in the reaction center accepts excited electrons and is reduced as a result Solar-powered transfer of an electron from a chlorophyll a molecule to the primary electron acceptor is the first step of the light reactions
There are two types of photosystems in the thylakoid membrane Photosystem II (PS II) functions first (the numbers reflect order of discovery) and is best at absorbing a wavelength of 680 nm The reaction-center chlorophyll a of PS II is called P680
Photosystem I (PS I) is best at absorbing a wavelength of 700 nm The reaction-center chlorophyll a of PS I is called P700
Linear Electron Flow During the light reactions, there are two possible routes for electron flow: cyclic and linear Linear electron flow, the primary pathway, involves both photosystems and produces ATP and NADPH using light energy
There are 8 steps in linear electron flow: 1. A photon hits a pigment and its energy is passed among pigment molecules until it excites P680 2. An excited electron from P680 is transferred to the primary electron acceptor (we now call it P680 + )
Figure 10.UN02 H 2 O CO 2 Light LIGHT REACTIONS NADP + ADP ATP CALVIN CYCLE NADPH O 2 [CH 2 O] (sugar)
Figure 10.14-1 Primary acceptor e 2 1 Light P680 Photosystem II (PS II) Pigment molecules
Figure 10.14-2 Primary acceptor 1 2 H + ½ + O 2 Light 3 H 2 O e e e 2 P680 Photosystem II (PS II) Pigment molecules
Figure 10.14-3 1 2 H + ½ + O 2 Light 3 H 2 O e e Primary acceptor e 2 P680 4 Electron transport chain Pq Cytochrome complex 5 Pc ATP Photosystem II (PS II) Pigment molecules
Figure 10.14-4 1 2 H + ½ + O 2 Light 3 H 2 O e e Primary acceptor e 2 P680 4 Electron transport chain Pq Cytochrome complex 5 Pc Primary acceptor e P700 6 Light ATP Photosystem II (PS II) Pigment molecules Photosystem I (PS I)
Figure 10.14-5 1 2 H + ½ + O 2 Light 3 H 2 O e e Primary acceptor e 2 P680 4 Electron transport chain Pq Cytochrome complex 5 Pc Primary acceptor e P700 Fd 7 e e 6 Electron transport chain 8 NADP + reductase Light NADP + + H + NADPH ATP Photosystem II (PS II) Pigment molecules Photosystem I (PS I)
3. H 2 O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680 +, thus reducing it to P680 P680 + is the strongest known biological oxidizing agent O 2 is released as a by-product of this reaction
4. Each electron falls down an electron transport chain from the primary electron acceptor of PS II to PS I 5. Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane Diffusion of H + (protons) across the membrane drives ATP synthesis
6. In PS I (like PS II), transferred light energy excites P700, which loses an electron to an electron acceptor P700 + (P700 that is missing an electron) accepts an electron passed down from PS II via the electron transport chain
7. Each electron falls down an electron transport chain from the primary electron acceptor of PS I to the protein ferredoxin (Fd) 8. The electrons are then transferred to NADP + and reduce it to NADPH The electrons of NADPH are available for the reactions of the Calvin cycle This process also removes an H + from the stroma
The energy changes of electrons during linear flow through the light reactions can be shown in a mechanical analogy
Figure 10.15 e e e Mill makes ATP e e e NADPH Photon e Photon Photosystem II ATP Photosystem I
Cyclic Electron Flow In cyclic electron flow, electrons cycle back from Fd to the PS I reaction center Cyclic electron flow uses only photosystem I and produces ATP, but not NADPH No oxygen is released
Figure 10.16 Primary acceptor Pq Fd Cytochrome complex Primary acceptor Fd NADP + reductase NADP + + H + NADPH Pc Photosystem II ATP Photosystem I
Some organisms such as purple sulfur bacteria have PS I but not PS II Cyclic electron flow is thought to have evolved before linear electron flow Cyclic electron flow may protect cells from light-induced damage
A Comparison of Chemiosmosis in Chloroplasts and Mitochondria Chloroplasts and mitochondria generate ATP by chemiosmosis, but use different sources of energy Mitochondria transfer chemical energy from food to ATP; chloroplasts transform light energy into the chemical energy of ATP Spatial organization of chemiosmosis differs between chloroplasts and mitochondria but also shows similarities
In mitochondria, protons are pumped to the intermembrane space and drive ATP synthesis as they diffuse back into the mitochondrial matrix In chloroplasts, protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma
Figure 10.17 MITOCHONDRION STRUCTURE CHLOROPLAST STRUCTURE Intermembrane space H + Diffusion Thylakoid space Inner membrane Matrix Electron transport chain ATP synthase Thylakoid membrane Stroma Key Higher [H + ] ADP + P i H + ATP Lower [H + ]
ATP and NADPH are produced on the side facing the stroma, where the Calvin cycle takes place In summary, light reactions generate ATP and increase the potential energy of electrons by moving them from H 2 O to NADPH
Figure 10.18 Photosystem II Light 4 H + Cytochrome complex Light Photosystem I Fd NADP + reductase 3 NADP + + H + H 2 O e - e- Pq 1 O 2 THYLAKOID SPACE ½ +2 H + 4 H + (high H + concentration) 2 Pc NADPH To Calvin Cycle STROMA (low H + concentration) Thylakoid membrane ATP synthase ADP + P i H + ATP
Figure 10.18a Photosystem II Cytochrome complex Light Photosystem I Light 4 H + Fd Pq H 2 O 1 THYLAKOID SPACE (high H + concentration) e e - - 2 ½ O 2 +2 H + 4 H + Pc STROMA (low H + concentration) Thylakoid membrane ATP synthase ADP + P i H + ATP
Figure 10.18b Cytochrome complex Light Photosystem I Fd NADP + reductase 3 NADP + + H + Pq 2 4 H + Pc THYLAKOID SPACE (high H + concentration) NADPH To Calvin Cycle ATP synthase ADP + P i H + ATP STROMA (low H + concentration)
Concept 10.3: The Calvin cycle uses the chemical energy of ATP and NADPH to reduce CO 2 to sugar The Calvin cycle, like the citric acid cycle, regenerates its starting material after molecules enter and leave the cycle The cycle builds sugar from smaller molecules by using ATP and the reducing power of electrons carried by NADPH
Carbon enters the cycle as CO 2 and leaves as a sugar named glyceraldehyde 3-phospate (G3P) For net synthesis of 1 G3P, the cycle must take place three times, fixing 3 molecules of CO 2 The Calvin cycle has three phases 1. Carbon fixation (catalyzed by rubisco) 2. Reduction 3. Regeneration of the CO 2 acceptor (RuBP)
Figure 10.UN03 H 2 O CO 2 Light LIGHT REACTIONS NADP + ADP ATP CALVIN CYCLE NADPH O 2 [CH 2 O] (sugar)
Figure 10.19-1 Input 3 CO 2, entering one per cycle Rubisco Phase 1: Carbon fixation 3 P P 3 P RuBP P 6 3-Phosphoglycerate P Calvin Cycle
Figure 10.19-2 Input 3 CO 2, entering one per cycle Rubisco Phase 1: Carbon fixation 3 P P 3 P RuBP P 6 3-Phosphoglycerate P 6 ATP 6 ADP Calvin Cycle 6 P P 1,3-Bisphosphoglycerate 6 NADPH 6 NADP + 6 P i 6 G3P P Phase 2: Reduction 1 G3P Output P Glucose and other organic compounds
Figure 10.19-3 Input 3 CO 2, entering one per cycle Rubisco Phase 1: Carbon fixation 3 P P 3 P RuBP P 6 3-Phosphoglycerate P 6 ATP 6 ADP 3 ATP 3 ADP Phase 3: Regeneration of RuBP 5 P G3P Calvin Cycle 6 1,3-Bisphosphoglycerate G3P 6 P P P 6 6 NADP + 6 P i NADPH Phase 2: Reduction 1 G3P Output P Glucose and other organic compounds
Concept 10.4: Alternative mechanisms of carbon fixation have evolved in hot, arid climates Dehydration is a problem for plants, sometimes requiring trade-offs with other metabolic processes, especially photosynthesis On hot, dry days, plants close stomata, which conserves H 2 O but also limits photosynthesis The closing of stomata reduces access to CO 2 and causes O 2 to build up These conditions favor an apparently wasteful process called photorespiration
Photorespiration: An Evolutionary Relic? In most plants (C 3 plants), initial fixation of CO 2, via rubisco, forms a three-carbon compound (3-phosphoglycerate) In photorespiration, rubisco adds O 2 instead of CO 2 in the Calvin cycle, producing a two-carbon compound Photorespiration consumes O 2 and organic fuel and releases CO 2 without producing ATP or sugar
Photorespiration may be an evolutionary relic because rubisco first evolved at a time when the atmosphere had far less O 2 and more CO 2 Photorespiration limits damaging products of light reactions that build up in the absence of the Calvin cycle In many plants, photorespiration is a problem because on a hot, dry day it can drain as much as 50% of the carbon fixed by the Calvin cycle
C 4 Plants C 4 plants minimize the cost of photorespiration by incorporating CO 2 into four-carbon compounds There are two distinct types of cells in the leaves of C 4 plants: Bundle-sheath cells are arranged in tightly packed sheaths around the veins of the leaf Mesophyll cells are loosely packed between the bundle sheath and the leaf surface
Sugar production in C 4 plants occurs in a threestep process: 1. The production of the four carbon precursors is catalyzed by the enzyme PEP carboxylase in the mesophyll cells PEP carboxylase has a higher affinity for CO 2 than rubisco does; it can fix CO 2 even when CO 2 concentrations are low
2. These four-carbon compounds are exported to bundle-sheath cells 3. Within the bundle-sheath cells, they release CO 2 that is then used in the Calvin cycle
Figure 10.20 Photosynthetic cells of C 4 plant leaf Mesophyll cell Bundlesheath cell Vein (vascular tissue) C 4 leaf anatomy Stoma The C 4 pathway Mesophyll cell PEP carboxylase Oxaloacetate (4C) Malate (4C) Bundlesheath cell Pyruvate CO (3C) 2 PEP (3C) ADP Calvin Cycle ATP CO 2 Sugar Vascular tissue
Figure 10.20a Photosynthetic cells of C 4 plant leaf C 4 leaf anatomy Mesophyll cell Bundlesheath cell Vein (vascular tissue) Stoma
Figure 10.20b The C 4 pathway Mesophyll cell PEP carboxylase CO 2 Oxaloacetate (4C) Malate (4C) PEP (3C) ADP ATP Bundlesheath cell Pyruvate CO (3C) 2 Calvin Cycle Sugar Vascular tissue
Since the Industrial Revolution in the 1800s, CO 2 levels have risen greatly Increasing levels of CO 2 may affect C 3 and C 4 plants differently, perhaps changing the relative abundance of these species The effects of such changes are unpredictable and a cause for concern
CAM Plants Some plants, including succulents, use crassulacean acid metabolism (CAM) to fix carbon CAM plants open their stomata at night, incorporating CO 2 into organic acids Stomata close during the day, and CO 2 is released from organic acids and used in the Calvin cycle
Figure 10.21 Sugarcane Pineapple 1 1 C 4 CO 2 CO 2 CAM Mesophyll cell Organic acid Organic acid Night Bundlesheath cell CO 2 Calvin Cycle 2 CO 2 Calvin Cycle 2 Day Sugar (a) Spatial separation of steps Sugar (b) Temporal separation of steps
Figure 10.21a Sugarcane
Figure 10.21b Pineapple
The Importance of Photosynthesis: A Review The energy entering chloroplasts as sunlight gets stored as chemical energy in organic compounds Sugar made in the chloroplasts supplies chemical energy and carbon skeletons to synthesize the organic molecules of cells Plants store excess sugar as starch in structures such as roots, tubers, seeds, and fruits In addition to food production, photosynthesis produces the O 2 in our atmosphere
Figure 10.22a O 2 CO 2 H 2 O Sucrose (export) Mesophyll cell H 2 O Chloroplast CO 2 Light NADP + LIGHT REACTIONS: Photosystem II Electron transport chain Photosystem I Electron transport chain ADP + P i ATP NADPH RuBP 3-Phosphoglycerate CALVIN CYCLE G3P Starch (storage) H 2 O O 2 Sucrose (export)
Figure 10.22b LIGHT REACTIONS Are carried out by molecules in the thylakoid membranes Convert light energy to the chemical energy of ATP and NADPH CALVIN CYCLE REACTIONS Take place in the stroma Use ATP and NADPH to convert CO 2 to the sugar G3P Return ADP, inorganic phosphate, and NADP + to the light reactions Split H 2 O and release O 2 to the atmosphere
Figure 10.23 MAKE CONNECTIONS The Working Cell Flow of Genetic Information in the Cell: DNA RNA Protein (Chapters 5 7) Movement Across Cell Membranes (Chapter 7) Energy Transformations in the Cell: Photosynthesis and Cellular Respiration (Chapters 8 10) Nucleus Nuclear pore 2 Protein 3 Ribosome mrna 1 mrna DNA Rough endoplasmic Protein reticulum (ER) in vesicle Vacuole Golgi apparatus 4 Plasma membrane 5 Vesicle forming Protein 6 7 Photosynthesis in chloroplast CO 2 H 2 O Organic molecules 8 Cellular respiration in mitochondrion O 2 ATP ATP ATP Transport pump ATP 11 9 10 Cell wall H 2 O CO 2 O 2
Figure 10.23a Nucleus Nuclear pore 2 Protein 3 Ribosome mrna 1 mrna DNA Rough endoplasmic Protein reticulum (ER) in vesicle Flow of Genetic Information in the Cell: DNA RNA Protein (Chapters 5 7)
Figure 10.23b Golgi apparatus 4 Vesicle forming Protein Plasma membrane 5 6 Cell wall Flow of Genetic Information in the Cell: DNA RNA Protein (Chapters 5 7)
Figure 10.23c 7 Photosynthesis in chloroplast Organic molecules 8 Cellular respiration in mitochondrion O 2 CO 2 H 2 O ATP ATP ATP ATP Transport pump 11 9 10 Movement Across Cell Membranes (Chapter 7) H 2 O CO 2 O 2 Energy Transformations in the Cell: Photosynthesis and Cellular Respiration (Chapters 8 10)
Figure 10.UN04a
Figure 10.UN04b Corn plant surrounded by invasive velvetleaf plants
Figure 10.UN05 Primary acceptor Primary acceptor Fd O 2 H 2 O Pq Cytochrome complex NADP + reductase NADP + + H + NADPH Pc Photosystem II Photosystem I
Figure 10.UN06 3 CO 2 Carbon fixation 3 x 5C 6 x 3C Regeneration of CO 2 acceptor 5 x 3C Calvin Cycle Reduction 1 G3P (3C)
Figure 10.UN07 ph 7 ph 4 ph 4 ph 8 ATP
Figure 10.UN08