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Photosynthesis. An experiment was carried out to determine how certain factors such as light intensity and availability of carbon dioxide, affected the rate of photosynthesis. The rate of photosynthesis was measure by the amount of oxygen produce (cm3/m

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Photosynthesis Abstract: An experiment was carried out to determine how certain factors such as light intensity and availability of carbon dioxide, affected the rate of photosynthesis. The rate of photosynthesis was measure by the amount of oxygen produce (cm3/min). A valid conclusion was made and most of the results were in accordance with the prediction, although there were some anomalies present. The errors and limitations were evaluated and some improvements were suggested. Introduction: Photosynthesis is an essential importance to organisms. It is the process by which green plants and a few organisms convert sunlight energy into chemical energy which is stored in molecules. Photosynthesis in green plants generally involves the green pigment chlorophyll and produces oxygen as a byproduct. This can be shown in the equation: The rate of photosynthesis is dependent on environmental factors such as light intensity, availability of carbon dioxide, availability of water, nutrients and temperature. The most important factors are the availability of light and carbon dioxide, which are limiting factors. Temperature is of some importance, however its influence is less clear because it is dependent on the other two limiting factors (light and CO2) and the temperature tolerance of the plant. The peak rate of photosynthesis is constrained by a limiting factor. This factor will prevent photosynthesis from rising above a certain level even though other factors essential for photosynthesis are improved. This liming factor will control the maximum rate of the photosynthetic reaction. ...read more.


This statement was confirmed by the results that were established. The results from the Longmans co-ordinated biology book (refer to appendix), also support this statement. The further the elodea was away from the lamp, the lower the light intensity became, and hence the rate of photosynthesis was slower. It was also observed that when the elodea was closer to the lamp, more bubbles were formed and were rising to the top of the test tube. As light is a limiting factor of photosynthesis, the closer the elodea is to the lamp, the more light is available there is, causing the rate of photosynthesis to become greater when the elodea is closer to the lamp. The further the elodea is away from the lamp, the less light is absorbs as the light from the lamp does not travel in a straight line and spreads out, causing a strain to the limiting factor of light, hence a decrease in the rate of photosynthesis. Light intensity will also affect how fast the light dependent stage of photosynthesis will form its products. The higher the light intensity, the more energy will become available for the electrons to be "excited", therefore photophosphorylation will take place at a higher rate. An increase in the rate of photophosphorylation will mean more ATP will be transported to the light independent stage to be used. The light independent stage will also occur at a higher rate increasing the rate of photosynthesis in the elodea. ...read more.


and elodea - Concentration of NaHCO3 - - Bubbles produces Secondary data source: Results from a Longmans Co-ordinated biology book Distance of lamp from elodea (cm) 100 80 60 40 20 0 Number of bubbles per minute 13 12 31 41 55 76 Concentration of NaHCO3 0 0.1 0.2 0.3 0.4 0.5 Average rate of O2 produced in 60mins 0.5 1.6 2.9 4.5 5.8 6 Glossary: Photophosphorylation: The production of ATP using the energy of sunlight Notes from today's lesson Diffusion/osmosis - permeability of a cell membrane - movement of particles across membrane - diffusion: movement of high concentrated particles to low concentrated particles across membrane - osmosis: movement of H2O particles - The cell is in a hypertonic solution, water will move out of the cell. The cell shrinks PLAYMOLYSIS � CRENATION (in blood) - The cell is in a hypotonic solution, water moves into the cell. The cell swells CYTOLYSIS � HEMOLYSIS - The cell is in an ISOTONIC solution. NO net movement of water molecule occurs DYNAMIC EQUILIBRIUM � No change Passive activity - O2, CO2, H2O, Amino Acids - enters the membrane Active - Protein, Carbohydrates, Ions Exocytosis, vesicles, endocytosis, pinocytosis - cell "drinking", phagocytosis Active transport: - Requires ATP - Occurs when substances transported: 1. against concentration gradient 2. are large molecules - Includes exo & endocytosis and membrane pumps In metabolism, NAD+ is involved in redox reactions, carrying electrons from one reaction to another. ?? ?? ?? ?? Michelle Seeto Year 12 Biology Mrs Nandlal ...read more.

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