Biological Sciences
Investigating Photosynthesis
"Investigating Photosynthesis" involves studying the process by which plants, algae, and some bacteria convert light energy into chemical energy to produce glucose and oxygen. Researchers explore the factors that affect photosynthesis, such as light intensity, carbon dioxide levels, and temperature, to understand its mechanisms and optimize plant growth. This research is crucial for improving agricultural practices and addressing environmental challenges.
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10 Key excerpts on "Investigating Photosynthesis"
eBook - PDF- Jean-Luc Wertz, Olivier Bédué(Authors)
- 2013(Publication Date)
- EPFL PRESS(Publisher)
Chapter 2 Photosynthesis, the Ultimate Beginning for Biorefineries 2.1 Introduction Photosynthesis is the main life process on Earth. [1] Through photosynthesis, land plants, algae and many species of bacteria, such as cyanobacteria, con- vert light energy from the sun into chemical energy needed for most biologi- cal functions. More precisely, photosynthetic organisms capture and use solar energy to transform water and atmospheric carbon dioxide (CO 2 ) into molec- ular oxygen (O 2 ) and carbohydrates such as glucose (Equation 2.1) [2, 3]: 6 CO 2 + 6 H 2 O + energy → C 6 H 12 O 6 + 6 O 2 (2.1) Carbohydrates can be used later to supply the energy needs to the cell. There- fore, photosynthesis is a process in which solar energy is stored in the bonds of carbohydrates. The amount of energy trapped by photosynthesis is immense, approxi- mately 100 terawatts (1 TW = 10 12 W), which is about six times larger than the power consumption of humanity (Figure 2.1). [4, 5] The energy produced Lignocellulosic Biorefineries 30 by photosynthesis forms the basis of virtually all terrestrial and aquatic food chains. Consequently, photosynthesis is the ultimate source of the carbon in the organic molecules found in most organisms. [6] Photosynthetic organisms convert about 100 billion tonnes of carbon into biomass per year. [7] Photosynthesis evolved early in the evolutionary history of life, when all forms of life on Earth were microorganisms and the atmosphere had much more CO 2 . [7] The first photosynthetic organisms probably evolved about 3,500 million years ago, and used hydrogen or hydrogen sulfide as sources of electrons, rather than water. Cyanobacteria appeared later, around 3,000 million years ago, and changed the Earth for ever when they began to oxygenate the atmosphere, beginning about 2,400 million years ago. This new atmosphere allowed the evo- lution of complex life such as protists.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Research World(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 9 Photosynthesis Composite image showing the global distribution of photosynthesis, including both oceanic phytoplankton and vegetation Overall equation for the type of photosynthesis that occurs in plants ________________________ WORLD TECHNOLOGIES ________________________ Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs , since they can create their own food. In plants, algae, and cyanob-acteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. Photosynthesis is vital for all aerobic life on Earth. As well as maintaining the normal level of oxygen in the atmosphere, nearly all life either depends on it directly as a source of energy, or indirectly as the ultimate source of the energy in their food (the exceptions are chemoautotrophs that live in rocks or around deep sea hydrothermal vents). The rate of energy capture by photosynthesis is immense, approximately 100 terawatts, which is about six times larger than the power consumption of human civilization. As well as energy, photosynthesis is also the source of the carbon in all the organic compounds within organisms' bodies. In all, photosynthetic organisms convert around 100–115 teragrams of carbon into biomass per year. Although photosynthesis can happen in different ways in different species, some features are always the same. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls. In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 1 Photosynthesis Composite image showing the global distribution of photosynthesis, including both ocea-nic phytoplankton and vegetation Overall equation for the type of photosynthesis that occurs in plants Photosynthesis is a process that converts carbon dioxide into organic compounds, es-pecially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, ________________________ WORLD TECHNOLOGIES ________________________ and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs , since they can create their own food. In plants, algae, and cyanoba-cteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. Photosynthesis is vital for all aerobic life on Earth. As well as maintaining the normal level of oxygen in the atmosphere, nearly all life either depends on it directly as a source of energy, or indirectly as the ultimate source of the energy in their food (the exceptions are chemoautotrophs that live in rocks or around deep sea hydrothermal vents). The rate of energy capture by photosynthesis is immense, approximately 100 terawatts, which is about six times larger than the power consumption of human civilization. As well as energy, photosynthesis is also the source of the carbon in all the organic compounds within organisms' bodies. In all, photosynthetic organisms convert around 100–115 teragrams of carbon into biomass per year. Although photosynthesis can happen in different ways in different species, some features are always the same. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls. In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- White Word Publications(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 14 Photosynthesis Composite image showing the global distribution of photosynthesis, including both oceanic phytoplankton and vegetation Overall equation for the type of photosynthesis that occurs in plants ________________________ WORLD TECHNOLOGIES ________________________ Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs , since they can create their own food. In plants, algae, and cyanob-acteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. Photosynthesis is vital for all aerobic life on Earth. As well as maintaining the normal level of oxygen in the atmosphere, nearly all life either depends on it directly as a source of energy, or indirectly as the ultimate source of the energy in their food (the exceptions are chemoautotrophs that live in rocks or around deep sea hydrothermal vents). The rate of energy capture by photosynthesis is immense, approximately 100 terawatts, which is about six times larger than the power consumption of human civilization. As well as energy, photosynthesis is also the source of the carbon in all the organic compounds within organisms' bodies. In all, photosynthetic organisms convert around 100–115 teragrams of carbon into biomass per year. Although photosynthesis can happen in different ways in different species, some features are always the same. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls. In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Research World(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 6 Photosynthesis Composite image showing the global distribution of photosynthesis, including both oceanic phytoplankton and vegetation Overall equation for the type of photosynthesis that occurs in plants ________________________ WORLD TECHNOLOGIES ________________________ Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs , since they can create their own food. In plants, algae, and cyanobacteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. Photosynthesis is vital for all aerobic life on Earth. As well as maintaining the normal level of oxygen in the atmosphere, nearly all life either depends on it directly as a source of energy, or indirectly as the ultimate source of the energy in their food (the exceptions are chemoautotrophs that live in rocks or around deep sea hydrothermal vents). The rate of energy capture by photosynthesis is immense, approximately 100 terawatts, which is about six times larger than the power consumption of human civilization. As well as energy, photosynthesis is also the source of the carbon in all the organic compounds within organisms' bodies. In all, photosynthetic organisms convert around 100–115 teragrams of carbon into biomass per year. Although photosynthesis can happen in different ways in different species, some features are always the same. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls. In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
In all, photosynthetic organisms convert around 100–115 teragrams of carbon into biomass per year. Although photosynthesis can happen in different ways in different species, some features are always the same. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls. In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane. Some of the light energy gathered by chlorophylls is stored in the form of adenosine triphosphate (ATP). The rest of the energy is used to remove electrons from a substance such as water. These electrons are then used in the reactions that turn carbon dioxide into organic compounds. In plants, algae and cyanobacteria, this is done by a sequence of reactions called the Calvin cycle, but different sets of reactions are found in some bacteria, such as the reverse Krebs cycle in Chlorobium . Many photosynthetic organisms have adaptations that concentrate or store carbon dioxide. This helps reduce a wasteful process called photorespiration that can consume part of the sugar produced during photosynthesis. ________________________ WORLD TECHNOLOGIES ________________________ Overview of cycle between autotrophs and heterotrophs. Photosynthesis is the main means by which plants, algae and many bacteria produce organic compounds and oxygen from carbon dioxide and water (green arrow). The first photosynthetic organisms probably evolved about 3,500 million years ago, early in the evolutionary history of life, when all forms of life on Earth were microorganisms and the atmosphere had much more carbon dioxide. They most likely used hydrogen or hydrogen sulfide as sources of electrons, rather than water. Cyanobacteria appeared later, around 3,000 million years ago, and drastically changed the Earth when they began to oxygenate the atmosphere, beginning about 2,400 million years ago.
eBook - PDF- Jean-Claude Leclerc(Author)
- 2003(Publication Date)
- CRC Press(Publisher)
Chapter 2 Photosynthesis and Plant Production 1. INTRODUCTION Photosynthesis, a major route for the uptake of energy, is the basis for all life functions. It appeared very early on earth through photosynthetic bacteria, since the atmosphere and water did not provide organic mol ecules or minerals yielding a large quantity of energy, or in sufficient concentrations, except in particular ecosystems. Photosynthesis may be considered to have developed in two major stages. First there was formation of a photochemical system with bacterial chlorophyll, which, when it absorbs light energy, can achieve a separation of charges that allows electron activation from substances (still sufficiently abundant in the terrestrial atmosphere) having Em7 values that could be considered averages, for example H2S (S/HS~ = -0.18 V), H2 (H2/2H+ + 2e = -0.43 V (but in fact the values are closer to zero in the natural environment, because of pH and low concentration), succinic acid (close to -0.1 V), and fumaric acid (close to 0 V). Electrons activated by light energy increase their potential to about -0.5 to -0.6 V. This allows reduction of several iron-sulphur proteins, more or less linked to the membrane, such as ferredoxin, which can, in turn, reduce NAD or NADP (Em7 = -0.32 V). Such reactions provide all the reductive energy at the cell level. NADHH+ and NAD+ have a difference of free energy of around 50 kcal/mole. The activation of electrons also allows, through the crossing of the membrane, the creation of a membrane potential. Finally, the membrane quinones, which are intermediary transporters of the electrons, also transport H+ from one side of the membrane to the other. Thus, in linkage with CFQand CF1 complexes, a photophosphorylation takes place, i.e., a synthesis of ATP exploiting the proto-motor force created by the light energy. This can also be illustrated in a diagram of the photosynthetic membrane of purple non-sulphur bacteria or green non-sulphur bacteria (Fig. 2.1).
eBook - PDF- William V Dashek, Marcia Harrison(Authors)
- 2010(Publication Date)
- CRC Press(Publisher)
CHAPTER 13 Photosynthesis J. Kenneth Hoober INTRODUCTION Sunlight provides a steady, abundant sup- ply to a world increasingly concerned about energy. The cause of this concern is a disconnect between inputs and outputs of energy forms. Forms of energy traditionally used to drive our mechanical devices differ from those that support living systems. Nuclear energy, fraught with waste prob- lems, hydroelectric, geothermal, or wind power, are all forms that can be used for mechanical devices but provide a minor fraction of the total energy input needed in the world economy. The bulk of the avail- able energy has been, and still is, derived from light energy from the sun. Technology has been developed to convert photons to electrons with photovoltaic cells that use absorption of light energy by silicon semi- conductor devices to generate electricity as the end product. This approach has great promise as a sustainable energy source but thus far does not compete economically with fossil fuels. Combustion of fossil fuels (coal, oil, and natural gas) is currently the major source of energy used to generate electricity and power machines. Fossil fuels are products derived from ancient photo- synthesis but, with few exceptions, are not directly usable by living systems. Life is also sustained by converting photons to electrons but through contemporary photo- synthesis. Except for organisms that live next to thermal vents in the deep oceans and those that can metabolize hydrocarbons, life is sustained by carbohydrates produced by photosynthesis. The major end product of photosynthesis is glucose 6-phosphate, the predominant starting material for storage forms of chemical energy and for synthesis of cellular components. When glucose 6-phosphate is metabolized in cells, the energy that was trapped in the molecule by photosynthesis is released to provide the energy required for synthetic reactions and growth.
eBook - PDFPhotosynthesis V2
Development, Carbon Metabolism, and Plant Productivity
- Govindjee, Unknown Govindjee(Authors)
- 2012(Publication Date)
- Academic Press(Publisher)
What is the current status of our knowledge about photosynthesis and the prospects for utilizing such knowledge? T h e following chapters (see 1. Photosynthesis 3 Fig. 1) attempt to present a relatively integrated view of the photosyn-thetic process in organisms, ranging from unicellular algae to the higher plants. T h e details of the mechanisms and control of the light-capturing processes, which lead to the production of adenosine triphosphate (ATP) and the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) that are needed for the fixation of carbon dioxide in photosynthesis, are contained in Volume 1 (see Govindjee, 1982). Subsequent details of the C 0 2 assimilation process and aspects of its control and integration with the growth of photosynthetic organisms are contained iri the present volume. T h e aim of these chapters has been to outline the basic status of our knowledge and especially to point out the present deficiencies and limitations, such that the problems and immedi-ate prospects for improving photosynthesis become evident. In the following paragraphs, we will briefly introduce some of the more prominent aspects of photosynthesis discussed in the following , CO* (OUT), Stomata ® Stomata CAM C 4 Cycle ® ® Algal CO, Pump (D r— (15+16> C0 2 <•> (See Separate NfclumejfLNADP jrf I ^ ADP 1 τ Electron Transport Ν ATDI^J Reductive Pentose ! β * A l r Phosohate Cvcle Photophosphorylation ^Genetics 8 Development (ED (CH 2 0) 1 Translocation o 2 « -RuBPase Photorespiration © τ Photosynthetic M o d e l i n g ® ] 0 0 * Applications @ Global Photosynthesis @ L Canopy Photosynthesis © FIG. 1. Schematic diagram of some of the relationships between the various chapters of this book (see text).
eBook - PDFAquatic Photosynthesis
Second Edition
- Paul G. Falkowski, John A. Raven(Authors)
- 2013(Publication Date)
- Princeton University Press(Publisher)
We strive here to examine the phenomenology of the short-term photosyn- thetic responses to variations in the aquatic environment. In the following chapter we examine the long-term changes and biogeochemical feedbacks that involve aquatic photosynthetic organisms. Let us begin with a brief look at how aquatic ecologists measure photosynthesis in nature and then consider acclimation responses within the framework of what we have learned in the earlier chapters. Estimating Photosynthesis in Aquatic Ecosystems Plant physiologists define the term gross photosynthesis, P g , as the light- dependent rate of electron flow from water to terminal electron acceptors (e.g., CO 2 ) in the absence of any respiratory losses (Lawlor 2001). It follows that this definition of P g is directly proportional to linear photosynthetic electron trans- port and, hence, gross oxygen evolution. 2 Gross photosynthesis accounts for all photosynthetic carbon fixation, whether the organic carbon formed becomes part of the organism or is excreted or secreted into the environment as organic carbon or is respired to CO 2 ; however, the relationship between gross oxygen evolution and CO 2 fixation will be modified by the photosynthetic quotient (see chapter 8). Respiratory losses in photosynthetic organism(s) can be defined as the rate of electron flow from organic carbon to O 2 (or, in the case of anaerobic photo- synthetic bacteria, to another electron acceptor) with the concomitant produc- tion of CO 2 . This definition includes all metabolic processes that contribute to 320 | Chapter 9 2 It should be noted that gross photosynthesis should be defined on the basis of oxygen evolution rather than carbon fixation. This difference is critical, especially if photorespiratory rates are high.
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