Heterosporous Plants

Heterosporous

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How plants have adapted or become acclimated to shade.

How plants have adapted or become acclimated to shade. Plants which grow in shady conditions have altered structurally and biochemically in order to cope with the low levels of light and harvest it efficiently. Low level light is rich in far-red light and plants have also adapted to make use of this. Shade plants have also had to make adjustments to cope with sudden high levels of light, for example during sunflecks. Whilst some plants show physiological adaptation, many changes are the result of genetic evolution. * Leaves are thinner with a shallow layer of palisade mesophyll cells and a patchy spongy mesophyll with air spaces (fig 1.). This uses less energy and resources to construct. Many shade plants (such as ferns) do not produce flowers for the same reason. * Shade leaves have more chlorophyll in the antenna systems to feed more energy to the reaction centres. There is also an increase in the number of reaction centres. * Shade light contains more light in the far-red range. The reaction centre of photosystem II (PSII) absorbs more light from the far-red range than photosystem I (PSI); hence there is a greater proportion of PSII to PSI. This is achieved by the presence of wide grana with larger numbers of stacked thylakoids (figure 2.). This enables the photosystems to be excited equally in far-red light. * Plants which grow in shade are often exposed to periods

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  • Level: University Degree
  • Subject: Biological Sciences
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Drought conditions, low and high temperatures, increased salt levels, pathogens and insects are common environmental stresses which plants are exposed to. Over time, plants have evolved unique mechanisms to respond to the stresses

Drought conditions, low and high temperatures, increased salt levels, pathogens and insects are common environmental stresses which plants are exposed to. Over time, plants have evolved unique mechanisms to respond to the stresses imposed in them. In response to pathogen infection, plants have two types of defence; constitutive and induced responses. Constitutive defences are those which are passive and always present in the plant. These defences are those such as the cuticle which is composed of waxes, cutin and pectin and the cell wall, composed of cellulose, pectin and lignin, both of which act as structural barriers against pathogens. There are preformed pathogen inhibitors such as saponins which disrupts pathogen cell membranes. For example, ?-tomatine in tomatoes acts against many fungal species. Other preformed inhibitors include alkaloids, phenols and tannins. Defence proteins are also present; lectins bind sugar groups such as chitin, which in fungal species binds to chitin in fungal walls and slows sungal growth. RIPs or ribosome inactivating proteins disrups viral replication by deactivating the plants ribosomes, therefore preventing cell replication and therefore also the viral pathogens replication. Hydrolases are present which break down the components of the pathogens and enzyme inhibitors inhibit enzymes which are used by the pathogen in the infection

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  • Level: University Degree
  • Subject: Biological Sciences
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Biotechnology - Penicillin

What is biotechnology? Biotechnology is the use of technology to construct products or perform tasks through the use of biological systems and organisms.1Through history we have gained more knowledge of how biotechnology is applied and have refined and created new techniques that have benefited different areas, such as agriculture and gene technology. The application of fungal products has been in use for hundreds of years in the production of foods such as cheese and soy products. Penicillium mould (Penicillium chrysogenum2 ) contains the antibiotic substance penicillin, which was successfully isolated in 1945. Since Ancient times, moulds have been used to treat infection. Ernest Duchesne was a physician who discovered through experimentation, that Penicillium glaucum was able to destroy the bacteria, Escherichia coli. In his research, Duchesne was able to cure typhoid by injecting a subject with P.glaucum, which was a remarkable achievement. But being an unknown, young student, Duchesne was not acknowledged with this discovery, and was prevented from continuing more research due to army research.3 Later similar discoveries were to be met with little attention until the 1920s. In 1928, a British bacteriologist Sir Alexander Fleming was studying the effects of Staphylococci, a genus of Gram-positive bacteria. He hypothesised that the mould, Penicillium notatum, was

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  • Level: University Degree
  • Subject: Biological Sciences
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Reproduction, sexual or asexual, is a means of survival of a particular species on the face of a planet. Angiosperms have many ways of reproducing themselves. It is of no surprise that the sex organs of a plant are in their flowers.

Introduction: Reproduction, sexual or asexual, is a means of survival of a particular species on the face of a planet. Angiosperms have many ways of reproducing themselves. It is of no surprise that the sex organs of a plant are in their flowers. Two major organs being: ovary and the anthers. Pollen is found primarily on the anthers, pollen [male gametophyte] is so widespread that we can find it almost everywhere, in the air we breathe, the soil we walk on etc. Physically it looks like a yellow, white or blue powdery substance. Pollen develops within the anther and after attaining maturity falls [by the means of air currents etc] onto the receptive stigma. The stored 'goodies' and RNA kick into action and start the most probably the most rapid growth of any plant cell. A tube known as the pollen tube grows from each pollen grain. This pollen tube grows toward the embryo sac. Eventually two sperm cells are deposited into the embryo sac where they fuse with the egg and form a zygote. Pollen germination is one of the most important processes insuring that a zygote is formed and the plant species continues and does not become extinct. Pollen germination is the stage when the pollen falls on the stigma and start growing the pollen tube. This process is vital since the ovary is located at the very bottom of the anther and is concealed from all 4 sides, making it almost impossible

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  • Level: University Degree
  • Subject: Biological Sciences
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Describe the major pathways and transformations involved in the atmospheric transport of Sulphur, produced as SO2 in combustion processes. Outline the major impacts of SO2 upon plants.

Describe the major pathways and transformations involved in the atmospheric transport of Sulphur, produced as SO2 in combustion processes. Outline the major impacts of SO2 upon plants. Sulphur is an essential nutrient for normal plant growth and development. The primary source of Sulphur is from the soil in the form of sulphate (SO42-), which is taken up by the roots and translocated to the leaves where most of it is reduced and assimilated into organic sulphur compounds. An important primary source of sulphur can be found in the atmosphere. 15 molecular species of Sulphur are found in the atmosphere, according to Berresheim et al (1995). Plants unable to acquire all the sulphur they need from the soil are able to use SO2 from the atmosphere or other volatile compounds such as H2S.When more SO2 is taken up from the atmosphere by plants then is needed, plants are adversely effected. SO2 is considered the most important phytotoxic molecule. Originally most sulphur combustion was carried out in widely scattered domestic appliances, increasingly with introduction of Pollution Abatement Legislation, energy generation became localised in large centralised facilities, such as those designed to produce electricity. These attempted to improve the local environment around them by building taller and taller stacks to disperse the gases higher into the atmosphere. Consequently, gases

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  • Level: University Degree
  • Subject: Biological Sciences
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I plan to investigate how environmental conditions affect the transpiration of plants.

Aims I plan to investigate how environmental conditions affect the transpiration of plants. Background Information The Sun provides the energy to turn the water in the plants into a vapour causing it to evaporate into the leave's internal air spaces before diffusing out of the stomata into the air. This is known as transpiration. As the water evaporates out of the top of the plant it creates a suction on the column of water below it in the xylem. The upwards force on the column of water created by transpiration and the downwards force due to gravity created a tension in the column of water. As the upwards pull is greater than the downwards pull the column of water moves up the xylem. Cohesion tension theory tells us that it is the evaporation of water from the leaves which causes the upwards movement of water. The water molecules have a high cohesion as they are polar and so are electrically attracted to each other. They are held together by hydrogen bonds. The column of water does not tend to break as it has a very high tensile strength from the bonds. The water is able to evaporate out of the leaf as the leaf has a high water potential and the air has a low water potential so the water molecules pass down the concentration gradient from the spongy and palisade mesophyll cells into the leave's internal air spaces before diffusing out into the air. Transpiration is

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  • Level: University Degree
  • Subject: Biological Sciences
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Is there evidence of plant succession with the old abandoned quarry at Maddocks Hill?

Is there evidence of plant succession with the old abandoned quarry at Maddocks Hill? Aims Throughout this study the following aims should be met: * What plant communities can be identified along the transect in Maddocks Hill Quarry * How does the occurrence of plant species vary along the transect? * Is plant diversity limited to entopic factors such as pH and soil moisture? * Does light and structure of plant life forms vary along the transect? * Can a definite plant succession be identified along a transect? Hypothesis "There will be taller plant life forms and different plant communities along a transect from the outer to inner parts of Maddocks Hill Quarry". Background Plant succession, a definition; "The natural and gradual replacement of one plant community by another." The process may begin on solid rock, soil or water, the end result being generally a forest tolerant (able to grow in the shade) trees. The stages in between may include moss, annual weeds, grasses, brush and intolerant trees (needing full sunlight) and mid-tolerant trees. The stages vary depending on the site and the process may take centuries to complete. The Ercall - 68 ha OS Map Ref. SJ 640 096 This is an attractive site adjacent to Telford and is part owned by the Shropshire Wildlife Trust and Telford and Wrekin Borough Council. Both the Ercall and The Wrekin are a Site of Special

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  • Level: University Degree
  • Subject: Biological Sciences
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My summer garden

My summer garden As the weather warmed, so did my heart. I felt at peace and had a lack of responsibility that I took for granted. I wanted to get the most out of the all to short nirvana by spending my time in my garden, I liked my personal time there, to be alone with my thoughts and not having to care about anything, which I suppose may have seemed selfish. In the other seasons, my garden was either cold, wet or simply unappealing. But in the summer, it all came to life and a desire grew inside me to meet and greet the new energy flowing out of the plants and animals. As I strayed from my back door my soul would be overtaken by an assimilating force of warmth, sounds and sights all hitting me like a gust of wind. The corners of my mouth would turn up uncontrollably and I would forget everything. My mind would be intoxicated by the pure nature before me, and I had no desire to damage the boundless balance of the tiny forest. Before me would lie the carpet of grass, usually brown and withered, which would dampen my mood, but this morbid image would never overtake the entire stretch of grass. The sides of the garden would be lined with plants and flowers as high as me. There was not much variation of colour, but I was content with the lush greens of the large leaves. Overshadowing those were larger trees left to grow at their own will, they obscured the dull fence from

  • Word count: 1157
  • Level: University Degree
  • Subject: Biological Sciences
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The Effect of Stomata Opening on Plant Transpiration

The Effect of Covered Stomata on Plant Transpiration Nezar Alsaeedi IB Biology Higher Year 1 Mr. Connors May 7, 2005 Abstract: The purpose of this study is to find the effect of covered stomata on plant transpiration. The experiment was designed to examine the changes in texture of four Devil's Ivy leaves (Epipremnum aureus) affected by covered stomata and rate of transpiration. One leaf was completely coated with Vaseline gel. The second leaf was coated only on the front surface, while the third leaf was coated on the back surface with gel. The fourth leaf was left uncoated as a control variable. The four leaves were hung on a rope (50cm. long), 10cm. apart from each other. The leaves were exposed to the same amount of sunlight, temperature (32 degrees Celsius), and humidity (about 70 percent). The changes in the texture of the four leaves were observed over a one-week interval. The results showed slight loss of turgidity for the completely coated leaf, moderate flexibility and folding edges in partially covered leaves (front-surface and back-surface coated leaves), and tremendous flexibility, softness, and complete inward folding of the edges of the uncoated leaf. According to the results, it is concluded that the uncoated leaf with uncovered stomata had the higher rate of transpiration than the other completely and partially coated leaves. Introduction:

  • Word count: 1908
  • Level: University Degree
  • Subject: Biological Sciences
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