The Process of Photosynthesis - Research Paper Example

PHOTOSYNTHESIS Student’s name Course Professor’s name University City Date Introduction Photosynthesis is a biochemical process that takes place in green plants to manufacture sugar which is used as the main source of energy for plant. The energy is used by the plant to sustain other biochemical activities that takes place in the plant (dewier et.al 2015, 4). The process of photosynthesis takes place in plant leaves, in particular cell components in the leaves known as chlorophyll. Chlorophyll is responsible for the green color that is observed in most of the photosynthetic plant leaves (Harris & Ashraf, 2013, 3). The process of photosynthesis involves the combination of water and carbon dioxide in the presence of light energy to form sugar and oxygen 6CO2 + 6H2O ---sunlight---> C6H12O6 + 6O2 The chlorophyll in the leaves absorbs the light energy which is used in the process of photosynthesis. Chlorophyll basically absorbs red and blue lights but reflects green light, this is responsible for the green color observed in most plant leaves. Photosynthesis takes place in two major processes; the light and the Calvin cycle. In the first process, plant leaves absorbs sunlight by chlorophyll and is converted into chemical energy in form of ATP and NADPH. The Calvin cycle dependent stage basically use the energy already manufactured in the light dependent stage to assemble carbohydrates from carbon dioxide (Anderson, T., 2015, 1). In the first step, some of the absorbed light is used to split water molecule into hydrogen and oxygen. The ATP formed in this process together with hydrogen atom is carried to the next process. The oxygen released in stage one sometimes a portion of it is used by the mitochondria but most of it is released into the atmosphere through the stomata. The second stage involves the use of ATP to combine the hydrogen molecule that was formed in the first process with carbon dioxide gas to from sugar. The sugar is finally stored as the energy molecule by the plant. Objectives 1. To identify and separate pigments in plants 2. establish pigment absorption of wavelength 3. examine how leaf structure is related to the function of photosynthesis 4. examine photosynthetic adoption of leaves in different environment Methods PART A Pigments of the leaves were extracted from the sample provided in the lab. About 1-2g of the leaf material was cut put into a mortar and grinded. Acetone (4ml) was then added into a test-tube together with the grinded leaf material and shaken. Water was also added into the mixture and shaken, finally petroleum ether (3ml) was also added into the mixture shaken and the mixture was allowed to settle for some minutes until different layers formed in the test-tube. Green later that formed in the test-tube was removed and put into a separate beaker. Six drops from the green solvent extract were obtained and applied on a chromatography paper one at a time; with every drop being let to dry thoroughly before another was applied. Acetone petroleum ether was used to separate different pigments on the paper. Each color band was cut from the paper and placed into separate solution to re extract the solvents. Spectrometer was used to measure the absorbance of the different pigments in a range of 380nm to 720nm. PART B Prepared slides of dicotyledonous plant leaves were examined under a compound microscope. X40 lens was used to observe a cross section of the leaf midiron half section and a drawing of it was made. Prepared slide of a eucalyptus leaf was also obtained and observed under the same procedure as for the typical dicot. Above and a drawing of that was also made. Results PART A. According to the graph, the absorbance of wavelengths was high in chlorophyll a, followed by chlorophyll b. relative absorbance was low in carotene and xanthophylls pigments. PART B I. transverse section of a typical dicot. Leaf blade PART B II: Transverse section of eucalyptus leaf blade Mesophyl layer in eucalyptus leaves appeared to have different layers of the spongy mesophyl. It seemed as if there was a high concentration of the mesophyl layer just immediately beneath the palisade layer. Discussions PART A. The relative absorbance of chlorophyll a and chlorophyll b were high compared to those of xanthophylls and carotene. This is because chlorophyll a and b are the abundant pigments in plant leaves and often shows maximum absorption of wavelength. Chlorophyll are the pigments in plant leaves that absorbs sunlight and in them, sunlight is converted to chemical energy that is used for the process of photosynthesis. Chlorophyll occurs in the chloroplasts which are abundant in the palisade layers. However, some spongy mesophyl layer also sometimes contain chloroplasts but in less amount. It exists in two forms; a and b. The variation in their concentration however differs depending on the plant species but in most cases, the ratio of chlorophyll a and b always exist at 3:3 or 4:3 (Artwellet.al 2013, 12) sometimes even as low as 2:2. The roles of both chlorophyll a and b differ depending on the light intensity. In well light areas, the role of chlorophyll a is basically associated with the manufacture of energy from the sunlight while the role of chlorophyll b in this case is mainly to harvests sunlight Chlorophyll b is the pigment responsible for the production of energy ATP. However, in area that is poorly light, the role of chlorophyll a of energy manufacturing is reduced more to harvesting light and the amount of chlorophyll b increases hence reducing the ratio. Xanthophylls exists in plant leaves as green pigments, they basically act as accessories for plant leaves, they do not require presence of light for them to carry out photosynthesis, as a result, they are always found even in younger plants. The main functions of xanthophylls are to absorb the light wavelength that chlorophyll cannot absorb. They basically protect the plan leaves from damage that may result from excess sunlight (Rayel, 2014, 6). Carotenes on the other hand are orange pigments in plant that transmit light energy absorbed from the chlorophyll. Blue wavelength from sunlight are also absorbed by carotene, this allow the spread of other long wavelength which forms yellow color. It is the pigment that is responsible for the yellow color observed in sunflower petals and other yellow leaves plants and flowers. Carotene also plays an important role of plant protection especially from the energy that is produced as a result of generating the singlet oxygen during the process of photosynthesis (Cole et.al 2013, 4) PART B The cuticle is the outermost layer of the plant leave which aids with regulation of water loss from the plant since water is a basic component of photosynthesis. It is waxy in nature and relatively thick to prevent plant water loss through the leaf surface. The epidermis layer is the layer found immediately after the cuticle. There are the upper and lower epidermis layers. The epidermis layer helps in regulation of gaseous exchange through the stomata. The palisade mesophyl and the spongy mesophyl are both located between the lower and the upper epidermis layers. The mesophyl layers basically help to regulate gaseous exchange between the chloroplast in the leaves. The palisade layer appears as cylindrical vertically arranged pills to the surface of the leaf. They are tightly packed and in most plants, they may occur in between one to three layers. The palisade layer is densely packed with chloroplasts which contain the pigment chlorophyll that is responsible for photosynthesis. The spongy mesophyl layer appears as loosely arranged cells with large spaces in between them. The spongy layer cats as a temporary storage for the materials synthesized by the chlorophyll in the palisade layer. The mesophyl layers also regulate light within the cells (vogelmman, 2013, 2). The major difference in the mesophyl structure of eucalyptus leaves is that the structures of the leaves mesophyl differ with different stages of growth. At juvenile stage, the leaves of eucalyptus are blue green in color and at adult stage; the leaves are dark green in color. The mesophyl cells distribution of eucalyptus leaves is bimodal of the form Ames/A1 with the maximum distribution occurring just below the adaxial and the abaxial area in the first layer of the palisade cells (vogelmman, 2013, 6). The difference between the eucalyptus leaves and the typical dicot leaves is that, for eucalyptus, since the tree always grow tall than ordinary dicot plants, the leaves are exposed to high sunlight intensity that can possibly damage the chloroplast. As a result, the palisade layer for eucalyptus is thicker and contains more chloroplasts than that of typical dicot plants to enable the leaves distributes sunlight evenly within the chloroplast without damaging the leaves. The stomata are mainly located on the underside of the leaves to regulate water loss and gaseous exchange (Flexaset.al, 2014, 6). The stomata are also very crucial in the process of photosynthesis. They open at night and remained relatively closed during the day. It through the stomata that carbon dioxide is absorbed by the plant and is used for the process of photosynthesis, and the oxygen generated from the process of photosynthesis is released into the atmosphere. Stoma also controls plant leaves water loss by transpiration. Surrounding the stomata on both sides are guard cells, the guard cells have a bean shaped and they control how the stoma opens and closes. When potassium ions are pumped into the guard cells, the osmotic pressure in the guard cell increases and water moves from the surrounding cells into the guard cells, the guard cells become turgid and the swollen, as a result the stomata opens. This is during high levels of concentrations of carbon dioxide. When the level of carbon dioxide reduces, the potassium ions that were in the guard cells are pumped out and in turn, the osmotic pressure within the guard cell reduces while that of the surrounding cells increases. Water therefore moves from the cells within the stomata into surrounding cells, the walls of the stomata shrinks and it closes. Stomatal opening and closing depends on the amount of carbon dioxide in the atmosphere, sunlight, the period of exposure to sunlight, water and the variety of the plant (Flexas et.al, 2014, 7). Chlorophyll is the major element in photosynthesis since it absorbs sunlight in the right wavelength that is required by plants to photosynthesize. However, chlorophyll does not operate on its own but instead with other pigments which enhance the efficiency and the rate of photosynthesis. The pigments also protect that plant from potential harm from sunlight. Other element of photosynthesis includes carbon dioxide and water. The leaf structure also plays a very crucial role in determining the level of photosynthesis, the stomata is the crucial factor in the leaf structure since it regulates gaseous exchange that is very necessary for the process of photosynthesis. Plant species is also an important factor in determining photosynthesis in plant leaves. Possible sources of error For chromatography, errors could possibly occur in the process of dipping the paper into the container with acetone petroleum ether. The paper is not supposed to touch the walls of the container. Also the drops are supposed to be allowed to dry out completely before another is added. Since there is no specific time set to assume that the drops are dry. It is very possible that additional drops are added before the previous ones are completely dry. This may lead to overlapping of the drops and hence interfere with the result. For part B, one major potential source of error is drawing an image of the specimen as observed under the microscope. The image appears as colored and therefore it is possible for one to represent the observation in drawing by coloring the various components as observed under the microscope which is a violation of the rules of drawings in biology only the outlines are supposed to be drawn. Improvements Improvements can be made especially for the chromatography procedure by establishing a time limit for which a drop of solvent on the paper can be confidently decided as completely dried out to avoid inconsistency. For example if research shows that on average the drops take certain minutes to dry. Then that time limit should be set as the standard. For the leaf anatomy, there are guidelines available on how to draw biological images. References Anderson, T Gentleman, C and Yool, A2015, ‘EMPOWER-1.0: efficient model of planktonic ecosystem written in R.’,Geosciences model development, vol, 8; 2231-2268 Artwell, J Kriedemann, E and Turnbull, G 2013, Plants in action. Melbourne Australia. Macmillan education publishers. Cole, J Likens E and Strayer, D 2013, Photosynthetically produced dissolved organic carbon: An important carbon source for planktonic bacteria Devmalkar VS Murumkar CV Salunkhe SM and Chavan SJ2014, Studies on the pigment chlorophyll isolation and estimation of different bryophytes for their biochemical properties’. Nat. Prod. Plant Resource, vol4, no, 2, pp56-61 Flexas J Carriquí M Coopman RE Gago J Galmés J Martorell S, Morales F Díaz-Espejo A 2014,‘Stomatal and mesophyl conductance to CO2 in different plant groups: underrated factors for predicting leaf photosynthesis responses to climate change?’Plant Science, vol26, pp 41-48. Harris, C and Ashraf, M 2013, Photosynthesis under stressful environment: an overview. 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