DOCSLIB.ORG

Photosynthesis: Light & Pigments

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Photosynthesis: Light & Pigments Starter: Recapping National 5 • What is the word equation for photosynthesis? • What are the 2 stages of photosynthesis? • What 2 processes occur in the light dependent stage? • What happens in the Calvin Cycle/Carbon fixation? PHOTOSYNTHESIS LIGHT AND PIGMENTS We are learning to • Understand how light is used in photosynthesis. I can Identify the fates of light falling on a plant leaf. Name the pigments used to trap light energy. Photosynthesis All food production is dependent ultimately upon photosynthesis. Most human food comes from a small number of plant crops a) Cereals b) Potato c) Roots d) legumes). Light energy in Photosynthesis When light strikes a leaf there are 3 fates of the outcomes Light can be …. 1. Reflected - Bounce off the surface. 2. Absorbed – pass into leaf & be converted into other energy. 3. Transmitted - Pass through the leaf unaffected. Name these processes? 12% reflected 100% light 83 % absorbed. a) ONLY 4% used for photosynthesis b)Remaining 79% lost as heat energy 5% transmitted Sample Calculation How do plants change sunlight into food? Photosynthesis SERIES of enzyme controlled reactions using special pigments inside the leaf to ABSORB light energy chemical energy (carbohydrate). Photosynthesis light energy chemical energy (carbohydrate). Photosynthetic Pigments Absorb light, allowing carbohydrates to be made Principal Pigment Chlorophyll a Accessory Pigments Chlorophyll b Carotene Xanthophyll Extracting Pigments Chromatography • Method for separating the 4 Pigments by their SOLUBILITY • The more soluble the pigment, the further it travel up the paper. Chromatography Twig Clip Chromatography Practical Extraction of Pigment 1. Grind plant tissue with sand & propanone • Break open cells & release pigment • Propanone to dissolve pigment 2. Filter mixture • Remove sand & debris Separation of Pigment 1. Repeatedly spot extract onto chromatography paper Ensure sufficient mixture is present 2. Spot above solvent level Prevents pigment dissolving out of paper 3. Run chromatogram in petroleum ether solvent Separate pigment As pigments have different solubilities in this solvent 4. Ensure paper does not touch sides Ensure solvent moves evenly up paper Photosynthetic Pigments Solvent Front Carotenoids Carotene ( Orange ) Most soluble Xanthophyll ( Yellow ) Chlorophyll a ( Blue-green ) Least soluble Chlorophyll b ( Dark green ) Spot Line pigment spot Calculting Rf Distance travelled by pigment Total distance travelled Calculting Rf Distance travelled by pigment Total distance travelled Red pigment 7.5/10 = 0.75 Blue pigment 2.5/10 = 0.25 Starter: Light Discussion • What is light • What colour is light? • What are the colours of the rainbow? PHOTOSYNTHESIS LIGHT AND PIGMENTS We are learning to • Describe the difference between an absorption spectra of the different pigments and the action spectra of photosynthesis. I can • Identify the absorption and action spectra from a graph. • Analyse and explain what they show. • Compare them Spectrum of light Most people cannot see below 400nm or above 700nm (visible part of the spectrum). Prism Activity ROYGBIV Light Spectrum • When a beam of light passes through a prism the VISIBLE spectrum of light is produced. The colour that we see, is the colour that has been reflected i.e. NOT ABSORBED If a colour has been absorbed it appears black to the human eye Spectrum Plant Absorption Spectrum Photosynthetic Pigments All these colours have been absorbed by the pigment. The colour we see is Green/blue - light that has been reflected/transmitted Plant Result The reflected wavelengths are mainly green. This is why chlorophyll appears green to the eye. Spectrum Absorption Spectra • The degree of absorption at each wavelength of light can be measured using a spectrometer. • The data is then used to plot a graph (Absorption Spectra) for each pigment. Role of pigments 1. Chlorophyll a and b complex molecules containing Magnesium. absorb light energy in red/blue regions Used for photosynthesis. 2.Carotene & xanthophyll absorb light mainly in green part of the spectrum. They pass on the energy to chlorophyll. Name this pigment? Why have accessory pigments Broaden the absorption spectrum and pass energy onto chlorophyll Action Spectrum Rate of photosynthesis at each wavelength of light. The higher the rate, the more effective the wavelength of light at providing energy for photosynthesis Action Spectrum Comparing Absorption & Action spectra Exam Tip Be careful not to mix up absorption spectrum. Absorption spectrum –colours of light absorbed by pigment Action spectrum – colours of light where photosynthesis occurs (does not exactly match absorption due to accessory pigments). `.
Load more

Recommended publications
  • Which Regions of the Electromagnetic Spectrum Do Plants Use to Drive Photosynthesis?
    Which regions of the electromagnetic spectrum do plants use to drive photosynthesis? Green Light: The Forgotten Region of the Spectrum. In the past, plant physiologists used green light as a safe light during experiments that required darkness. It was assumed that plants reflected most of the green light and that it did not induce photosynthesis. Yes, plants do reflect green light but human vision sensitivity peaks in the green region at about 560 nm, which allows us to preferentially see green. Plants do not reflect all of the green light that falls on them but they reflect enough for us to detect it. Read on to find out what the role of green light is in photosynthesis. The electromagnetic spectrum: Light Visible light ranges from low blue to far-red light and is described as the wavelengths between 380 nm and 750 nm, although this varies between individuals. The region between 400 nm and 700 nm is what plants use to drive photosynthesis and is typically referred to as Photosynthetically Active Radiation (PAR). There is an inverse relationship between wavelength and quantum energy, the higher the wavelength the lower quantum energy and vice versa. Plants use wavelengths outside of PAR for the phenomenon known as photomorphogenesis, which is light regulated changes in development, morphology, biochemistry and cell structure and function. The effects of different wavelengths on plant function and form are complex and are proving to be an interesting area of study for many plant scientists. The use of specific and adjustable LEDs allows us to tease apart the roles of specific areas of the spectrum in photosynthesis.
    [Show full text]
  • Photobiology
    Photobiology Jode Himann |Nemalux Research | 12.01.2017 Photobiology is the study of light and its effect on living things. There has been a great deal of study on photobiology in the area of agriculture. This interest is growing because of the science becoming more refined and the marketplace developing. Some random notes and an initial Nemalux fixture spectra is shown. McCree Curve: K. J. McCree (1970) studied and developed the action spectrum, absorption and quantum yield curves of photosynthesis in crop plants. The action spectrum is commonly known as the McCree Curve. McCree curve shows the wavelengths shows the relative photosynthesis response in the between 400-700 nm (commonly known as photosynthetically active region or PAR) for plants growth. This is also known as generalized PAR curve. McCree also showed the relative quantum yield and relative absorption for 400-700nm region. This work has been the basis of all of the researches that followed until now. 1 Image : Econolux Action curve vs Absorption curve: Action curve shows the wavelengths that are most effective for photosynthesis. On the other hand Absorption curve shows the wavelengths that are absorbed by Chlorophylls (Chlorophyll A & B) and Cartenoids. Image : Econolux It is easily understood that most of the absorption happens in 400-500nm (blue) and 600-700nm (red) region. There’s a very little absorbance in the 500-600nm (green) region. However, there are still 70% of the 550nm absorptance is present as the integrity of leaf increases. Different studies shows that Chlorophylls responds to Blue (400 – 500nm) and Red (600-700nm) wavelengths.
    [Show full text]
  • Measuring the Short-Term Plant Photosynthetic Response to Varying Light Quality Using Light Emitting Diodes (Leds)
    Measuring the Short-term Plant Photosynthetic Response to Varying Light Quality Using Light Emitting Diodes (LEDs) Michael A. Schwalb Department of Bioresource Engineering McGill University Montreal, Quebec, Canada A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Master of Science December, 2013 © Michael Schwalb, 2013 1 Abstract Light emitting diodes (LEDs) emit narrow bandwidth light and have the potential to increase the spectral efficiency of supplemental lighting in greenhouses by optimizing spectral output for plant growth and yields. At the moment of writing, data describing the plant response to varying light quality and quantity was limited. The objective of this research was to examine photosynthetic response of plants to varying light quality and quantity and to gather photosynthetic response data that could be used to design an optimal spectrum for a prototype LED array for plant growth experiments. The action spectrum of tomato (Solanum lycopersicum), lettuce (Lactuca sativa) and petunia (Petunia × hybrida) seedlings was measured at three irradiances (30, 60 and 120 µmol m-2 sec-1) using LED arrays with peak wavelengths from 405nm – 700nm and a bandwidth of 25nm (full width at half maximum). The action spectrums for all plant species at all three irradiances were characterized by localized blue and red action peaks within the range of 430 to 449 nm and 624 to 660 nm respectively. A peak also occurred at 595 nm for 30 µmol m-2 sec-1.The photosynthetic response of tomato, lettuce and petunia to varying red (660nm) and blue (430nm) wavelengths with and without background broadband radiation was also measured.
    [Show full text]
  • Printable PDF: RGB Light Source And
    6400-18 RGB Light Source & 5 Photosynthetic Assimilation Summary non-photochemical processes (e.g. heat; ● The 6400-18 Red, Green, Blue (RGB) Blankenship, 2002). However, because other Light Source can deliver 2000 μmol m-2 wavelengths of light are absorbed and are s-1 white light†. equally capable of driving photosynthesis, it ● Three LED colors can be controlled is important to not only describe an absorp- independently to deliver any combina- tion spectrum, but also the photosynthetic tion desired. action spectrum for the absorbed light. OTE OTE ● Absorption spectrum of a plant drives the effectiveness of each color’s photosyn- Action spectra describe the amount of CO2- thetic response. fixed or O2-released at a particular wave- ● LED light should be normalized to the length across the absorption spectrum for a absorption spectrum of the plant. leaf. As is the case for absorption spectra, N N action spectra vary greatly between species Action spectrum of plants and RGB (McCree, 1972). For many C3 species, there is greater assimilation when plants are output illuminated with red light and to a lesser Not all incident radiation is absorbed by extent blue light than when illuminated with actively photosynthesizing leaves. Depending green light. on wavelength, light incident on a leaf may be reflected, transmitted through the leaf or The 6400-18 Red, Green, Blue (RGB) Light absorbed by the light harvesting complex to Source is a composite LED source comprised drive the light reactions. The proportion of of multiple diodes embedded within a tile. light absorbed at any particular wavelength The LED wavelength peaks of this commer- varies between and within species, and cially available tile are 460, 522 and 635 ± 5 frequently between individual leaves in a nm, corresponding to light in the blue, green plant canopy, dependent on canopy position and red regions of the light spectrum respec- and the history of the leaf.
    [Show full text]
  • Photosynthesis Photosynthesis
    Unit 5 Photosynthesis UNIT 5 PHOTOSYNTHESIS Structure 5.1 Introduction 5.4 Role of Sunlight Objectives Electromagnetic Spectrum 5.2 Basic Concepts – Historical Absorption and Action Background Spectrum Earlier Investigations Absorption of Photons – Energy States of Chlorophyll Development of Concept – Formulation of Equation of 5.5 Summary Photosynthesis 5.6 Terminal Questions 5.3 Photosynthetic Pigments 5.7 Answers Essential Pigments : Chlorophylls Accessory Pigments Non-Photosynthetic Pigments and Photoreceptors 5.1 INTRODUCTION In this Unit you will be studying the plant pigments including non- photosynthetic pigments and sunlight, which are required for photosynthesis— a process by which green plants and certain other organisms transform light energy into chemical energy in the form of sugars. This sugar can then be converted to other carbohydrates or other food materials like fats and proteins. The general importance of the process was recognized as long ago as 2000 years. The biblical saint, Isaiah, who lived between 700-600 B.C. said “All flesh is grass” recognizing that all food chains are finally traced to plants. Plants are also responsible for the fossil fuels such as petroleum, oil, and coal, which represent products of photosynthesis carried out millions of years ago in the carboniferous era. It is through this process that plants continuously purify air during daytime and thus allow animals to breathe. The overall importance of this process is best expressed in the words of Eugene Rabinowitch, one of the great authors and
    [Show full text]
  • Horticulator Photosynthetic Active Radiation (PAR)
    Application Note Vorteile Horticulturevon LED-Beleuchtung in | Microcosm GartenbauanwendungenLED it grow! Dies hat zur Folge, dass der Wirkungsgrad sehr stark von den Wellenlängen zu hohe oder zu geringe Mengen liefern (Abbildung 5). Strompreisen abhängig ist (Abbildung 4). Mit steigendem Strompreis Außerdem kann die Lichtrezeptur nicht an eine Pflanzenentwicklung werden die Einsparungen bei der Implementierung eines LED- angepasst werden (Abbildung 6). Derzeit gibt es eine Reihe von Projekten, Beleuchtungssystems deutlich größer. die die Lichtrezeptur (und andere Parameter) auf die Wachstumsphase der Pflanze abstimmen. Dabei kommen Kameras zum Einsatz, meist im 4 Lichtqualität sichtbaren oder infraroten Bereich. Der ultraviolette Bereich (UVA und UVB, 280 bis 400 nm) ist derzeit ein sehr interessantes Thema im Der Hauptvorteil von LEDs liegt in der Möglichkeit, das Gesamtspektrum Pflanzenanbau. Sonnenlicht besteht aus 9 % UV (Prozent PPF), während des Lichts anzupassen und zu optimieren. Dies kann genutzt werden, um HID-Quellen einen festen Wert von 0,3 bis 8 % UV-Strahlung (Prozent die photosynthetische Effizienz zu erhöhen und zu verbessern und PPF) emittieren[10]. Mit LEDs lässt sich die Belichtung sehr einfach steuern. Entwicklungsphasen zu steuern[8] aber auch, um die Menge an Eine unzureichende UV-Strahlung kann bei einigen Pflanzenarten die ungenutztem Licht und1. damit Essence Energie zu of reduzieren. Light Aufgrund ihrer Entwicklung3. What unterbrechen does [11]a. HIDplant-Quellen need? haben eine minimale fernrote monochromatischen Leistung können mehrere LEDs mit Strahlung (710 bis 740 nm), die LEDs effizient erzeugen können. unterschiedlichen WellenlängenLight is the verwendet visible part werden, of the um electromagnetic art-, sorten- und DieThe Be dimportanteutung d eparameterr fernrote nis S Photosynthetictrahlung wird i n ANO004 erklärt.
    [Show full text]
  • Spectrum of Light As a Determinant of Plant Functioning: a Historical Perspective
    life Review Spectrum of Light as a Determinant of Plant Functioning: A Historical Perspective Oxana S. Ptushenko 1, Vasily V. Ptushenko 2,3,4,* and Alexei E. Solovchenko 5,6 1 Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia; [email protected] 2 A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia 3 N.M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119334 Moscow, Russia 4 N.N. Semenov Federal Research Center for Chemical Physics, 119991 Moscow, Russia 5 Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia; [email protected] 6 Institute of Medicine and Experimental Biology, Pskov State University, 180000 Pskov, Russia * Correspondence: [email protected] Received: 20 January 2020; Accepted: 12 March 2020; Published: 17 March 2020 Abstract: The significance of the spectral composition of light for growth and other physiological functions of plants moved to the focus of “plant science” soon after the discovery of photosynthesis, if not earlier. The research in this field recently intensified due to the explosive development of computer-controlled systems for artificial illumination and documenting photosynthetic activity. The progress is also substantiated by recent insights into the molecular mechanisms of photo-regulation of assorted physiological functions in plants mediated by photoreceptors and other pigment systems. The spectral balance of solar radiation can vary significantly, affecting the functioning and development of plants. Its effects are evident on the macroscale (e.g., in individual plants growing under the forest canopy) as well as on the meso- or microscale (e.g., mutual shading of leaf cell layers and chloroplasts).
    [Show full text]
  • The Action Spectrum, Absorptance and Quantum Yield of Photosynthesis in Crop Plants
    AgriculturalMeteorology- Elsevier Publishing Company, Amsterdam- Printed in The Netherlands THE ACTION SPECTRUM, ABSORPTANCE AND QUANTUM YIELD OF PHOTOSYNTHESIS IN CROP PLANTS K. J. McCREE Institute of Life Science and Biology Department, Texas A and M University, College Station, Texas (U.S.A.) (Received October 15, 1970) ABSTRACT McC'~E, K. J., 1972. The action spectrum, absorptance and quantum yield of photosynthesis in crop plants. Agrie. MeteoroL, 9: 191-216. The measurements were made to provide a basis for discussion of the definition of "photo- synthetically active radiation". The action spectrum, absorptance and spectral quantum yield of CO2 uptake were measured, for leaves of 22 species of crop plant, over the wavelength range 350 to 750 nm. The following factors were varied: species, variety, age of leaf, growth conditions (field or growth chamber), test conditions such as temperature, COs concentration, flux of monochromatic radiation, flux of supplementary white radiation, orientation of leaf (adaxial or abaxial surface exposed), For all species and conditions the quantum yield curve had 2 broad maxima, centered at 620 and 440 nm, with a shoulder at 670 nm. The average height of the blue peak was 70Yo of that of the red peak. The shortwave cutoff wavelength and the height of the blue peak varied slightly with the growth conditions and with the direction of illumination, but for the practical purpose of defining "photosynthetically active radiation" the differences are probably insignificant. The action spectrum for photosynthesis in wheat, obtained by HOOVER in 1937, could be duplicated only with abnormally pale leaves. INTRODUCTION The aim of these measurements is to provide a factual basis for a standard definition of "photosynthetically active radiation".
    [Show full text]
  • Estimation of the Photosynthetic Action Spectrum: Implication for Primary Production Models
    MARINE ECOLOGY PROGRESS SERIES Vol. 146: 207-223, 1997 Published January 30 Mar Ecol Prog Ser Estimation of the photosynthetic action spectrum: implication for primary production models Margareth N. ~yewalyanga'~~.',Trevor platt3, Shubha sathyendranathlr3 'Department of Oceanography, Dalhousie University, Halifax. Nova Scotia, Canada B3H 451 'Institute of Marine Sciences, University of Dar-es-Salaam, PO Box 668 Zanzibar, Tanzania 3Biological Oceanography Division, Bedford Institute of Oceanography, Box 1006, Dartmouth, Nova Scotia, Canada B2Y 4A2 ABSTRACT A slmple method for estimating the photosynthetic action spectrum is developed The method uses the shape ot the absorption spectrum of phytoplankton p~gments,scaled to the magnitude of the initial slope of the photosynthesis-light curve as established for broad-band illun~~nationThe method was tested by comparing the estimated action spectra with those measured dunng a crulse in the North Atlant~cIn the fall of 1992 The agreement between the constructed and the measured spec- tra was good Both the measured and constructed action spectra were then used to compute daily water-column pnmary production (PZT)using a spectrally resolved model The results showed that, at most of the stations, the PZTc~mputedusing the constructed action spectrum was not significantly dif- ferent from PZ calculated using the measured spectrum Daily water-column pnmary production was also computed at each station uslng the average shape of the measured action spectra (spectra aver- aged over all stations), scaled to the magn~tudeof broad-band initial slope at that station The results were sim~larto the PZTvalues computed using the action spectra constructed for individual stations The errors that may affect the constructed act~onspectrum are assessed through a sens~tivityanalysis The analysis suggests that, for our data, the presence of photosynthet~callyinactive p~gmentscauses negligible errors in the computed P,.
    [Show full text]
  • About Photosynthesis
    Reference 4 More about Photosynthesis Photosynthesis Requires Light Most life on Earth depends on the continual release of light energy from the Sun. Of the sunlight that reaches our planet, only about one percent is involved in photosynthesis. The rest is absorbed or reflected by clouds or dust in Earth’s atmosphere or by Earth’s surface. Visible light, which is only a small fraction of the energy coming from the Sun, consists of a spectrum of colors, each with a different wavelength and energy content (figure R4.1). When light strikes an object, it may be transmitted, absorbed, or reflected. In plant cells, several different pigments can absorb light energy. Each pigment is a chemical compound that absorbs only certain wavelengths of light and reflects or transmits all others. Green plants, for example, appear green because chlorophyll absorbs most wavelengths of visible light except green, which it reflects. Figure R4.1: Radiations from the Sun form a continuous series. The range of radiations that organisms can detect with the eyes—visible light—is roughly the same range that plants use. Shorter wavelengths (blue light) are more energetic than longer wavelengths (red light). Leaves are green because chlorophyll absorbs red and blue wavelengths and only a little green. Chlorophyll mainly reflects green light. Photosynthesis depends on the green pigment chlorophyll, which occurs in several forms. Chlorophyll a apparently is present in all photosynthetic plants; other forms may be present in different combinations. Figure R4.2 shows an absorption spectrum (a simple graph that displays the percentage of light absorbed by a pigment at each wavelength) for chlorophylls a and b.
    [Show full text]
  • 40. G. Drews, "Contributions of Theodor Wilhelm Engelmann on Phototaxis, Chemotaxis, and Photosynthesis"
    Photosynthesis Research (2005) 83: 25–34 Ó Springer 2005 Historical corner Contributions of Theodor Wilhelm Engelmann on phototaxis, chemotaxis, and photosynthesis Gerhart Drews Institut fu¨r Biologie 2, Mikrobiologie, Albert-Ludwigs-Universita¨t, Scha¨nzlestr. 1, 79104 Freiburg, Germany (e-mail: [email protected]; fax: +49-761-2032779) Received 3 September 2004; accepted in revised form 30 October 2004 Key words: chemotaxis, photokinesis, photosynthetic oxygen production, phototaxis, purple bacteria, T. W. Engelmann Abstract Theodor Wilhelm Engelmann (1843–1909), who had a creative life in music, muscle physiology, and microbiology, developed a sensitive method for tracing the photosynthetic oxygen production of unicellular plants by means of bacterial aerotaxis (chemotaxis). He discovered the absorption spectrum of bacterio- purpurin (bacteriochlorophyll a) and the scotophobic response, photokinesis, and photosynthesis of purple bacteria. Abbreviations: B – Bacterium; C – Chromatium Introduction The life and work of Theodor Wilhelm Engelmann The fame of people celebrated and honored during Theodor Wilhelm Engelmann was born on their lifetimes often dwindles shortly after their November 30, 1843, as the son of well-known death. This holds true for the sciences and bibliographer and publisher Wilhelm Engelmann humanities as well and is a normal process if the and his wife Christiane Therese Hasse, in Leipzig, achievements were restricted to the celebrity’s Germany. He was raised in a stimulating atmo- time. Some are forgotten, even though their con- sphere of humanities and science. At the presti- tribution to their field was comparable to the gious Thomas School in Leipzig, young achievements of those found in bibliographies, Engelmann developed a predilection for the cello encyclopedias, and textbooks of the present time.
    [Show full text]
  • Motility in Unicellular and Filamentous Cyanobacteria 11 Bianca Brahamsha and Devaki Bhaya
    Motility in Unicellular and Filamentous Cyanobacteria 11 Bianca Brahamsha and Devaki Bhaya Abstract to respond to various environmental signals such Both unicellular and filamentous cyanobacte- as light or to chemical gradients. In some cases, ria exhibit diverse types of motility, including the motility apparatus required for movement the ability to move on surfaces and to swim in and the signal transduction cascade that allows liquids. Motile behaviour can be regulated such for a response to environmental cues are well that cyanobacteria can respond to important understood, while in others they remain to be environmental signals such as light or chemi- discovered. It is also apparent that motility is a cal gradients. In some cases, components of the complex and regulated phenomenon where more motility machinery, such as Type IV pili that than one mechanism for movement can be used allow certain unicellular species to move on sur- depending on the lifestyle and environmental faces have been characterized. In others, as is the conditions (Jarrell and McBride, 2008). For case for swimming in certain marine unicellular instance, some bacteria encode both flagella and species, and gliding in filamentous genera, the Type IV pili (TFP), while others can produce motility apparatus has yet to be identified. We extracellular materials that aid or are required for describe here recent advances that have led to motility. the identification of multiple photoreceptors and Unicellular and filamentous cyanobacteria as novel proteins involved in motility. The complex well as many photosynthetic microalgae exhibit signal transduction pathways governing motile motile behaviours, and their responses to light behaviour and attempts to model this behaviour are particularly well studied (Gomelsky and Hoff, are discussed.
    [Show full text]