Biology controlled experiments Essays

Biology controlled experiments Essays Biology controlled experiments Paper Biology controlled experiments Paper Photosynthesis is the process in which plants manufacture food. The rate of photosynthesis is affected by a number of factors: temperature being one of them.   Other factors include carbon dioxide concentration, light levels, availability of water and nutrients. Temperature can be a limiting factor to the process of photosynthesis.   Increasing temperature twice for example from 100C to 200c could double the rate of photosynthesis.   Increasing temperature increases the rate of photosynthesis since the plant’s enzymes will be working closer to their optimum temperature. Temperature also increases the kinetic energy of molecule in the cells increasing efficiency of making sugars.   Temperature beyond enzyme’s optimum will cause a drop in the rate of photosynthesis.   A greater increase in temperature above the optimum denatures enzymes so plants will not be able to photosynthesize (Factors affecting photosynthesis; A level Biology project: www.neiljohan.com) One of the byproduct of photosynthesis is oxygen. Therefore by monitoring the rate at which a plant is emitting oxygen, a conclusion can be made regarding the plant’s rate of photosynthesis. Question How does Elodea plant’s rate of photosynthesis behave with increase in temperature? Which temperature level is Elodea plant’s rate of photosynthesis optimum? Hypothesis The rate of photosynthesis of Elodea plant increases with increase in temperature until the plant reaches its optimum Prediction If all other factors limiting photosynthesis rate are kept constant, then the rate of photosynthesis will be directly proportional to increase in temperature up to a certain level after which it will start declining. Methodology Temperature is the independent variable of the experiment while the dependent variable is air (oxygen).   All other factors affecting photosynthesis e.g. light levels, availability of water, carbon dioxide level and plant nutrients are kept constant. Materials needed include: photosynthometer, Elodea plant, Beaker of water, lamp, ice, Hot water and thermometer. A piece of elodea plant is cut and put in a beaker of water with the cut end kept up by supporting it with a paper clip.   Temperature of water is varied from time to time by adding hot water to warm it up or ice to cool it down. A thermometer is used to determine the required temperature level. The independent variable (air) is measured by a photosynthometer with a tubing of 1 mm diameter. It measures the volume of air (oxygen) given off by the elodea plant.   The volume of air is measured by pulling the tube and seeing how much air bubble has increased in length using the rule of the tubing. A temperature range of 150c – 300c can be used with two replicates to obtain suitable conclusions.