...– Directly or indirectly, Ps nourishes almost the entire living world – Ps occurs in plants, algae, certain other protists, and some prokaryotes • Autotrophs sustain themselves without eating anything derived from other organisms – Autotrophs are the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules – Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules • 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 (organic molecules) and O2 © 2011 Pearson Education, Inc. Concept 10.1: Photosynthesis converts light energy to the chemical energy of food Ps stores energy in complex organic molecules, whereas cellular respiration releases it. • Chloroplasts are structurally similar to and likely evolved from photosynthetic bacteria – Their structural organization allows for the chemical reactions of Ps • Leaves are the major locations of Ps – Their green color is from chlorophyll, the green pigment within chloroplasts • Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf – Each mesophyll cell contains 30–40 chloroplasts (see next slide’s figure) © 2011 Pearson Education, Inc. • CO2 enters and O2 exits the leaf through microscopic pores called stomata • Chlorophyll is in the membranes of thylakoids (connected...
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...TRANSMISSION ELECTRON MICROS... About Me STUDY PORTAL View my complete profile Followers Physics term paper on TRANSMISSION ELECTRON MICROSCOPE Friday, January 21, 2011 by STUDY PORTAL in Labels: TERM PAPERS Acknowledgement It is a pleasure of mine to find myself penning down these lines to express my sincere thanks to my teacher to give me this opportunity of preparing this Term Paper, to enhance my professional practice. I express my deep sense of gratitude to my physics teacher to give me knowledge about the topic and concept related to this particular Term Paper. Without his guidance I cannot imagine to complete my Term Paper on time. In the last, I want to thank my parents, without whom nothing was possible. Contents 1. What is TEM. 2. Principle of TEM. 3. Working of TEM. 4. Uses of TEM 5. Limitations of TEM. 6. References The Transmission Electron Microscope: The transmission electron microscope (TEM) is a scientific instrument that uses electrons instead of light to scrutinize objects at very fine resolutions. They were developed in the 1930s when scientists realized that electrons can be used instead of light to "magnify" objects or specimens under study. View inside cell via sections magnification 120,000 * 50,000X Principle: The transmission electron microscope (TEM) operates on the same basic principles as the light microscope but uses electrons instead of light. What you can see with a light microscope...
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...photon model of light is necessary to explain the results. • To study the effect of intensity of light on photoelectric experiment. • To estimate the Planck’s constant, h through the simulation. • To be determine how to calculate the wavelength of light, the work function of the metal, or the stopping potential, if given the other two. Beginning with the plate made of sodium. Keep all the parameters constant except for the colour (wavelength) of the light and display all the graphs available. 1. Have the light source turned on at very low intensity and battery set to ZERO volts. Vary the wavelength of the light source (from Infra Red to Ultra Violet) until electrons just begin to be ejected from the sodium surface. State the wavelength and note the speed of the electrons. What is the corresponding frequency of the electromagnetic wave? Why is it called threshold frequency? Intensity is set at 1%. Wavelength = 370-395nm, energy = 1eV, speed of electrons = of different speed, some fast and some slow. The corresponding frequency will be 7.59 ( 1014 Hz – 8.11 ( 1014 Hz. It is called threshold frequency because it is the minimum frequency needed in order for the photoelectric to take place. 2. Repeat the instruction 1 above but allow the light to shine on the metal for a longer time before the wavelength is varied. Is your finding different as found in 1? Justify your finding. Yes, wavelength = 400nm (longer). The longer the light shines on the...
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...Ashley Cooper Biology 240 Week 1 Photosynthesis: Photosynthesis is the process in which plants convert light energy into chemical energy (glucose). Photosynthesis takes place in the chloroplasts of plants. * The Light Dependent Reaction: The light dependent reaction takes place in the membrane of the thylakoid membrane of a chloroplast and the lumen of the thylakoid. As light hits the thylakoid (the pigment) the Chlorophyll is absorbing the energy from the photons. Chlorophyll absorbs the red and blue light and reflects the green light. This is why most plants we see are green. Once chlorophyll absorbs enough energy, it releases two electrons. To replace the electrons chlorophyll uses light to split water into Oxygen and Electrons. The Oxygen is then released as a byproduct and the chlorophyll keeps the electrons. The kept electrons are stored in the Primary Electron Acceptor. Once the electron is released it moves down the Electron Transport Chain. The movement of the electrons through the Electron Transport Chain result in the creation of Adenosine Tri-phosphate (ATP), which is a form of energy. This activates the proton pump-to-pump hydrogen ions into the lumen of the thylakoid. At this time two different situations happen simultaneously. Either there is a continuation of the hydrogen or the electron moved down the Electron Transport Chain end up in Photosystem 1. In the hydrogen continuation, hydrogen has just been pumped into the lumen of the...
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...Quantum Theory Electrons behave like particles in some experiments, and like waves in others. The electron's 'wave/particle duality' has no real analogy in the everyday world. The quantum theory that describes the behavior of electrons is a cornerstone in modern chemistry. Quantum theory can be used to explain why atoms are stable, why things have the color they do, why the periodic table has the structure it does, why chemical bonds form, and why different elements combine in different ratios with each other. Light and electrons both behave quantum mechanically. To understand the experimental basis for the quantum theory, we have to begin our discussion with light. Waves * Waves are an oscillation that moves outward from a disturbance (ripples moving away from a pebble dropped into a pond) Properties of waves | property | definition | symbol | SI units | velocity | distance traveled per second | c | m/s | amplitude | peak height above midline | A | varies with type of wave | wavelength | peak-to-peak distance | | m | frequency | number of peaks passing by per second | | s-1 (called Hertz) | | * relationship between frequency and wavelength * distance per cycle × cycles per second = distance per second = c * examples * The speed of sound in air is 330 m/s. Humans can hear sounds with wavelengths between 17 m and 17 mm. What is the highest sound frequency that is audible? * interference * constructive interference:...
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...captures light energy. These first steps are called the light reactions. Plant cells involved in photosynthesis are packed with organelles called chloroplasts. Within these chloroplasts are flattened membrane sacks stacked up like coins—the thylakoids. Groups of proteins and pigment molecules are embedded within the thylakoid membranes. The structure and arrangement of these molecules creates a system of interacting components that work together to capture the energy from light and convert it into chemical energy. These collections of molecules are called photosystems and they come in two types called photosystem I and photosystem II. The two photosystems lie in close proximity to each other. In fact, they are wired together with an electron transport chain. Trying to keep track of the details of the various photosynthetic reactions is a bit much. Refer to the light reaction illustrations in your text and please explore the animations on your CD-ROM. The animations present a clear picture of the how the photosystems work. Here, let’s focus on an overview of the light reactions with an emphasis on the inputs and outputs. Remember there are two photosystems; each collects light photons. When a photosystem absorbs a photon, an electron is bumped to a higher energy level. The high-energy electrons from photosystem II are used to produce ATP, while the high-energy electrons from photosystem I are used to produce NADPH, a shuttle molecule that carries high- energy electrons to other...
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...to form sugars and other complex compounds for growth. There are two basic processes in photosynthesis: light-dependent and light-independent. Light-dependent process, a temperature-independent reaction where light energy is absorbed by the photosynthetic pigments and transformed into chemical energy which is used for water, splitting into oxygen molecule, proton (H+) for driving ATP during phosphorylation, and electron (e-) which is being passed down the electron transport chain to yield NADPH. Light–independent, temperature-dependent reaction occurs to form carbohydrate and water molecule by the assimilation of carbon dioxide, driven by NADPH and ATP from light-dependent reaction. In this practical, DCPIP, a blue dye is used. DCPIP turns into colourless as it is reduced by accepting electrons. The rate of DCPIP turns into colourless indirectly gives an estimation on the rate of electron transport, as well as the rate of photosynthesis. Aim: To determine the rate of DCPIP turns into colourless/photosynthetic electron transport in isolated chloroplasts from silverbeet leaves under different type of treatments. The rate of DCPIP turns into colourless is indicated by measuring the absorbance using a spectrophotometer. Hypothesis: The faster the DCPIP turns into colourless, the more rapid is the decrease in absorbance over time, the faster the electron being transported in silverbeet leaves, thus, the higher the rate of photosynthesis. Methods: ...
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...The electron transport chain is found in both mechanisms of cellular respiration and photosynthesis. Cellular respiration uses a series of redox reactions to transfer electrons and protons across a membrane to form an electrochemical gradient whereas photosynthesis harvests the light as its energy source to form its electrochemical gradient. This proton electrochemical gradient is used to power ATP synthesis via ATP synthase. The simplified overall reactions of photosynthesis and cellular respiration exhibit reciprocity to each other in that the starting material of cellular respiration begins with H¬2O and the breakdown of glucose and ends with CO¬¬2 and H2O to create ATP. Photosynthesis initially utilizes energy from light combined with inorganic...
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... very prettily a-moving. any Ibiggest sort. . . up to this time. The The had ever seen had a very strong and biggest sort. .and shot through into water (or swift motion, . bent their body the curves in going forwards. . . does through the water. The spittle) like a pike Moreover, the other animalcules were in suchspun round numbers, second sort. . . oft-times enormous like a top. that allthese were.far more in number." . . and the water. . seemed to be alive." Modern Cell and Molecular Biology Cytology the study of cell structure Genetics the study of the behavior of genes Biochemistry the study of the chemistry of living systems Cell and Molecular Biology Figure 1-2 Resolving Power of the Human Eye, the Light Microscope, and the Electron Microscope ? The study of cells •1830’s...
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...dark red) The Bohr Atom Thompson: plum pudding Rutherford: nucleus in a sea of electrons. Bohr: planetary model. Wave velocity = (wavelength)(frequency). Review of wave mechanics. The electromagnetic spectra: The type of wave is determined by its wavelength and frequency. Speed of light = 2.998 x 108 m/s A light wave has a frequency of 1.74 x 1017 hertz. What is its wavelength? What type of light is it? Planck’s Hypothesis Light is given off in bundles of energy called quanta. E = h( Energy = planck’s constant * wave frequency h = 6.626 x 10-34 J/hz Energy Problems A photon of light is found to have 3.63 x 10-22 Joules of energy. What is the wavelength of this light wave? A photon of light is found to have a wavelength of 5.00 x 102 nm. What is the energy of a photon of this light wave? Planck’s Hypothesis Atomic Spectra: produced when an electron moves from a higher to lower energy level, giving off light in the process. (E = Ehi - Elo = h( = hc/( Ex. For the yellow line in the sodium spectra (( = 589.0 nm), find its frequency, quantum energy, and the energy released by one mol of sodium electrons.What is the energy difference between two energy levels of Na? Planck’s Hypothesis ( ( 5.090 x 1014s-1 (E = 3.373 x 10-19 J For one mol of electrons: (E = 203.1 kJ Hence a two energy level difference = 203.1 kJ/mol Bohr Model Bohr postulated that an electron moves about the nucleus in a circular orbit of a fixed radius. The emission spectra...
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...well as the reasoning behind how this could produce a signal. Electromagnetic radiation is produced by accelerating charges. In the radio transmitter, electrons oscillate up and down and are thus accelerating. An electron will exert a force on another electron when they are some distance away, like charges repel. When the electron in the transmitter oscillates up and down, the direction of the force it exerts changes since the source of the force (the oscillating electron) is moving. It takes some time for the change in this direction of the force to be felt since this change is communicated or propagated out at the speed of light. In addition, the horizontal component of this force is canceled by the positive charges in the transmitting antenna. So, the resulting force is an oscillating force that pushes vertically on electrons. This force propagates out as a wave as the signal travels at the speed of light. b) How does your antenna work to detect this electromagnetic signal produced when radio stations broadcast? Include the physics principles that support your description of how this signal is detected. Electromagnetic radiation is a form of energy that exerts a steadily oscillating force on charges (electrons)... first the force will be exerted strongly in one direction then this will reverse and the electron will feel a strong force in the opposite direction, and the cycle will continue. In the radio antenna,...
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...It is synthesis of carbohydrates from CO2 and H2O by utilising the light energy in which O2 is the bye product. The overall reaction of photosynthesis can be represented by the equation: Light and 6CO2 + 12H2O Chlorophyll → C6 H12 O6 + 6 H2O + 6 O2 • From carbohydrates, the other organic substances of the plant are formed. • Green plants utilise only 1% of solar energy that falls on this planet to fix 2 billion tones of CO2 every year. • The algae of oceans carry out 90% of global photosynthesis. Chloroplast • It is double membrane bound cell organelle involved in photosynthesis. • It has two smooth surfaced, selectively permeable membranes with periplastidial space between them. • The enzyme rich region surrounded by inner membrane is called as Stroma. It is involved in dark reaction of Photosynthesis. • The flattened sack like structures of stroma are known as Thylakoids. • Stack of thylakoids is known as Granum. • The region where one granum is in contact with other granum is called as appressed region. • Grana are linked by unstacked thylakoids known as Stroma lamellae or Fret membranes. • The cavity of each thylakoid is called as Lumen or Intrathylakoid space. • Thylakoid membrane has two structurally different photosynthetic units called Photo System I and Photo system II. Photo System • Each photosystem has two components known as Reaction centre and Antenna – Chlorophyll complex or Light Harvesting Complex. • Reaction centre is also called as core complex...
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...be used to measure the wavelength’s of light. Abstract To determine the wavelengths of the visible spectral lines of Ne with high precision and to compare calculated with handbook values. To determine the experimental uncertainty of the wavelength values (i.e. the precision of the experiment). To observe the line spectrum of an unknown source and determine the wavelengths of one particular order. Theory Figure 1 Figure 1 Light can be split up into a range between 400 nm to 700nm, this is called the visible spectrum, which is part of the electromagnetic spectrum. The largest of the visible spectrum is red which is about 700 nm and the smallest wave is violet which is approximate 400 nm. From figure 1 it can be seen the colours of light being separated by a triangular prism the longer waves (red) and shorter waves (blue) being separated. Diffraction, when waves meet a gap in a barrier they carry on through the gap, the waves spread out to wide extent into the area beyond the gap, as can be seen in figure 2. But the extent on how it does spread depends on the size of the gap, the larger the gap the less spreading which is done by the wave, the smaller the gap the more spreading the waves does. This exact phenomenon is the reason you can hear someone round the corner of a building before you see them or while driving your car you can still receive a radio signal miles away from the transmitter. Figure 2 Figure 2 When light passes through a small slit it can be...
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...1. Energy Level: the specific energies an electron in an atom or other system can have 2. Quantum: the amount of energy needed to move an electron from one energy level to another 3. Quantum Mechanical Model: the modern description, primarily mathematical, of the behavior of electrons in atoms 4. Atomic Orbital: a mathematical expression describing the probability of finding an electron at various locations; usually represented by the region of space around the nucleus where there is a high probability of finding an electron 5. Electron Configurations: the arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms 6. Aufbau Principle: the rule that electrons occupy the orbitals of lowest energy first 7. Pauli Exclusion Principle: an atomic orbital may describe at most two electrons, each with opposite spin direction 8. Spin: a quantum mechanical property of electrons that may be thought of as clockwise or counterclockwise 9. Hund’s Rule: electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible 10. Amplitude: the height of a wave’s crest 11. Wavelength: the distance between adjacent crests of a wave 12. Frequency: the number of wave cycles that pass a given point per unit of time; frequency and wavelength are inversely proportional to each other 13. Hertz: the unit of frequency; equal to one cycle...
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...Photoelectric Effect E LEGANT C ONNECTIONS IN P HYSICS “On a Heuristic Point of View Concerning the Production and Transformation of Light”[1] was the first of the five papers published by Albert Einstein in his 1905 “miraculous year.”[2] In that paper, Einstein introduced the concept of “light quanta,” or “photons” as we call them today. The quantum of action was introduced into physics by Max Planck in 1900.[3] Planck derived the thermal equilibrium energy distribution for electromagnetic radiation (also called the “blackbody problem” because of the experimental apparatus). The quantity of interest was dr/df where r denotes the energy density and f the frequency (Fig. 1). No one had been able to derive dr/df from the first principles of statistical mechanics. One serious problem was in the high frequencies, which contributed infinite energy when one integrated over all frequencies to obtain the total energy! Planck thought about the charged particles whose simple harmonic motion generated harmonic electromagnetic waves of the same frequency. He discovered that if he assumed a particle oscillating with frequency f could carry only the discrete energies 0, hf, 2hf, 3hf..., where h was a constant, he could derive the distribution function: dr/df = (8ph/c3) f 3 (e hf/kT − 1)−1 , where c denotes the speed of light in vacuum, k Boltzmann’s constant, and T the absolute temperature. This function fit the data provided h was assigned the value 6.6×19−34...
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