How plant absorb sunlight


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How plant absorb sunlight

  2. 3. <ul><li>What is sunlight? </li></ul><ul><li>What are the role of sunlight to human and plant? </li></ul><ul><li>How plant absorb sunlight? </li></ul><ul><li>What are the effect of direct sunlight? </li></ul><ul><li>- skin cancer </li></ul>
  3. 4. <ul><li>Light is form of energy known as electromagnetic energy, also called electromagnetic radiation. Electromagnetic energy travels in rhythmic waves </li></ul><ul><li>2) This is usually during the hours known as day. When the direct radiation is not blocked by clouds, it is experienced as sunshine,acombination of bright light and heat. Radiant heat directly produced by the radiation of the sun is different from the increase in atmospheric temperature due to the radiative heating of the atmosphere by the sun's radiation . </li></ul>
  4. 5. VISIBLE SUNLIGHT <ul><li>The entire range of radiation is known as the electromagnetic spectrum. The segment most important to life is the narrow band from about 380nm to 750nm. </li></ul><ul><li>This radiation is known as visible light . </li></ul><ul><li>Visible light is one way energy uses to get around. Light waves are the result of vibrations of electric and magnetic fields, and are thus a form of electromagnetic (EM) radiation. Visible light is just one of many types of EM radiation, and occupies a very small range of the overall electromagnetic spectrum. We can, however, directly sense light with our own eyes, thus elevating the role of this narrow window in the EM spectrum because of its significance to us. </li></ul>
  5. 6. The human eye has developed the ability to see best in the type of light given off by the Sun. Our eyes are most sensitive to the colors from yellow through green.
  6. 7. White light is dispersed by a prism into the colors of the optical spectrum.
  7. 8. Sunlight spectrum <ul><li>The first process in photosynthesis is light absorption. Visible light is a form of radiant energy. </li></ul><ul><li>It make up a small part of the also known as electromagnetic spectrum which means the range of wavelengths or frequencies of electromagnetic radiation extending from gamma rays to the longest radio waves including visible light. </li></ul>
  8. 9. The Electromagnetic spectrum and the visible wavelengths used as the energy source For photosynthesis
  9. 10. <ul><li>The radiation that we detect as visible light has wavelength between about 700nm,(red light) & 400nm (blue light). </li></ul><ul><li>The entire wavelength (700nm & 400nm) combines together, as white light </li></ul><ul><li>Although radiated in apparently continuous beams that follow a wave path through space, the energy of light interact with matter in discrete unit called photons. </li></ul><ul><li>Each photons contains fixed amount of energy that is inversely proportional to its wavelengths </li></ul><ul><li>Means That… THE SHORTER THE WAVELENGTH, THE GREATER THE ENERGY OF PHOTONS </li></ul>
  10. 12. Role of sunlight <ul><li>In human </li></ul><ul><li>UVB radiation (290-315 nm) is the primary source of vitamin D </li></ul><ul><li>Vitamin D promote bone growth and mineralization </li></ul>
  11. 13. <ul><li>In plant </li></ul><ul><li>Photosynthesis </li></ul><ul><li>plant metabolism rely on wavelength red and blue </li></ul><ul><li>red wavelength- stimulate co₂ absorption </li></ul><ul><li>blue wavelength – stimulate cell structures. </li></ul>
  12. 14. Role of sunlight <ul><li>Photomorphogenesis </li></ul><ul><li>sunlight provides the necessary information for proper plant development </li></ul><ul><li>In seed germination </li></ul><ul><li>Respond available light waves using specialized photoreceptor called phytochrome. </li></ul><ul><li>Red light-regulate stem growth </li></ul><ul><li>Blue light- absorbed by phototropin </li></ul><ul><li> phototropin regulate oxygen-co2 gas exchange </li></ul>
  13. 15. <ul><li>Flowering </li></ul><ul><li>Process requires energy provided by different coloured light </li></ul><ul><li>Red light- stimulate flower growth process </li></ul><ul><li>Blue light- regulate rate of growth </li></ul>
  14. 16. How plant absorb sunlight? <ul><li>The leaf cells (mainly palisade cells in the palisade layer in the mesophyll layer) contain organelles called chloroplasts which have a pigment called chlorophyll. </li></ul><ul><li>That chlorophyll absorbs light energy from the sun and convert it into chemical energy. </li></ul>
  15. 17. <ul><li>Chlorophyll </li></ul><ul><ul><li>Consist of 2 parts; </li></ul></ul><ul><li>(i) porphyrin; head </li></ul><ul><li>(ii)long hydrocarbon @ phytol; tail </li></ul><ul><ul><li>Made up of 4-nitrogen containing pyrrole ring </li></ul></ul><ul><ul><li>Mg 2+ in the center of the ring </li></ul></ul><ul><ul><li>Four species of chlorophyll : a, b, c and d </li></ul></ul>
  16. 18. <ul><li>Chlorophyl a </li></ul><ul><li>A type of chlorophyll that is most common and predominant in all oxygen-evolving photosynthetic organisms such as higher plants, red and green algae. </li></ul><ul><li>It is best at absorbing wavelength in the 400-450 nm and 650-700 nm of the electromagnetic spectrum </li></ul>
  17. 19. <ul><li>Chlorophyll b </li></ul><ul><li>-A yellow-green chlorophyll pigment which occurs only in plants and green algae. </li></ul><ul><li>- It functions as a light harvesting pigment that pass on the light excitation to chlorophyll a </li></ul><ul><li>- It absorbs well at wavelength of 450-500 nm and 600-650 nm of the electromagnetic spectrum </li></ul>
  18. 20. <ul><li>Chlorophyll c </li></ul><ul><ul><li>A form of chlorophyll that occurs only in algae, specifically the diatoms, dinoflagellates and brown algae. </li></ul></ul><ul><ul><li>Its role is to pass on the light excitation to chlorophyll a </li></ul></ul>
  19. 21. <ul><li>Chlorophyll d </li></ul><ul><ul><li>A type of chlorophyll found in marine red algae and cyanobacteria </li></ul></ul><ul><ul><li>absorbs the infrared light of the electromagnetic spectrum </li></ul></ul><ul><ul><li>It is the major chlorophyll in cyanobacteria living in an environment depleted in visible light but abundant in infrared light. </li></ul></ul>
  20. 22. Mg N N N N CH 3 CHO CH2 CH CHO O CH2 CH2 C=O CH CH2 Chlorophyll a Chlorophyll c Chlorophyll d Chlorophyll b pheophytin I II III IV
  21. 23. <ul><li>Chlorophyll b,c and d similar to chlorophyll a, expect : </li></ul><ul><ul><li>Chlorophyll b : that a formyl group replaces the methyl group on ring II </li></ul></ul><ul><ul><li>Chlorophyll c : that it lacks the long hydrocarbon tail </li></ul></ul><ul><ul><li>Cholorphyll d : that a –O-CHO group is substituted on ring I </li></ul></ul>
  22. 25. <ul><li>Chlorophyll does not absorb strongly green of the visible light spectrum (490-550nm) </li></ul><ul><li>Maximum absorption: blue light (425-490nm) and red (640-700nm) </li></ul>
  23. 26. Do plants absorbs all the available sunlight? <ul><li>No, just selected wavelengths are absorbed efficiently. If plants could trap and absorb all of the light that strikes them, they would be black </li></ul>
  24. 27. <ul><li>the absorption varies with wavelength Chlorophyll does not absorb all the wavelengths of visible light equally. </li></ul><ul><li>Chlorophyll a, the most important light-absorbing pigment in plants, does not </li></ul><ul><li>absorb light in the green part of the spectrum. Light in this range of wavelengths is reflected. This is the reason why chlorophyll is green and also why plants (which contain a lot of chlorophyll) are also green. </li></ul>
  25. 28. Direct sunlight <ul><li>has a luminous efficacy of about 93 lumens per watt of radiant flux, which includes; </li></ul><ul><ul><li>infrared light </li></ul></ul><ul><ul><li>Visible light </li></ul></ul><ul><ul><li>ultraviolet light. </li></ul></ul>
  26. 29. Effect of direct sunlight <ul><li>Plant </li></ul><ul><ul><li>Plants produce their own energy, they require sunlight to conduct photosynthesis. </li></ul></ul><ul><ul><li>When there is not enough light available for photosynthesis and therefore not enough ATP available for cellular processes and growth.  </li></ul></ul><ul><ul><li>Photoperiodism (the length of light that each plant will react to) is stimulated by a pigment called phytochrome. </li></ul></ul><ul><ul><li>Various forms of phytochrome react to these varying wavelengths, depending on which wavelength of light is absorbed by the plant. </li></ul></ul>
  27. 30. Effect of direct sunlight <ul><li>Effects on human health </li></ul><ul><ul><li>The body produces vitamin D from sunlight </li></ul></ul><ul><ul><li>excessive sunlight </li></ul></ul><ul><ul><ul><li>Skin cancer </li></ul></ul></ul><ul><ul><ul><li>Skin aging- skin photodamage </li></ul></ul></ul><ul><ul><li>A lack of sunlight, </li></ul></ul><ul><ul><ul><li>seasonal affective disorder (SAD), a serious form of the &quot;winter blues&quot;. </li></ul></ul></ul><ul><ul><li>A recent study indicates that more exposure to sunshine early in a person’s life relates to less risk from multiple sclerosis (MS) later in life </li></ul></ul>
  28. 31. Effect of direct sunlight <ul><li>Skincancer </li></ul><ul><ul><li>Anyone can get skin cancer, but it is more common in people who; </li></ul></ul><ul><ul><ul><li>Spend a lot of time in the sun or have been sunburned </li></ul></ul></ul><ul><ul><ul><li>Have light-colored skin, hair and eyes </li></ul></ul></ul><ul><ul><ul><li>Have a family member with skin cancer </li></ul></ul></ul><ul><ul><ul><li>Are over age 50 </li></ul></ul></ul>
  29. 32. Sign of skin cancer <ul><li>The ABCDEs of melanoma skin cancer are: </li></ul><ul><ul><li>Asymmetry. One half doesn't match the appearance of the other half. </li></ul></ul><ul><ul><li>Border irregularity. The edges are ragged, notched, or blurred. </li></ul></ul><ul><ul><li>Color. The color (pigmentation) is not uniform. Shades of tan, brown, and black are present. Dashes of red, white, and blue add to a mottled appearance. </li></ul></ul><ul><ul><li>Diameter. The size of the mole is greater than 1/4 inch (6 mm), about the size of a pencil eraser. Any growth of a mole should be evaluated. </li></ul></ul><ul><ul><li>Evolution (not shown in the picture). There is a change in the size, shape, symptoms (such as itching or tenderness), surface (especially bleeding), or color of a mole. </li></ul></ul>
  30. 33. Video = 5 sign of skin cancer