• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

An investigation of the effects of the quantity of light on the rate of photosynthesis in Elodea

Extracts from this document...


Biology GCSE Coursework "An investigation of the effects of the quantity of light on the rate of photosynthesis in Elodea" Planning I am going to investigate the effect of the quantity of light on the rate at which a piece of Elodea photosynthesises. The term photosynthesis means making food in the light. It is the basis of all food chains and webs, because green plants are able to use sunlight as an energy source. Green plants are called primary producers, and the food they make from simple inorganic substances is passed through the eco system. Plants take in two raw materials, water from the soil, and CO2 from the air, and along with minerals, produce all the organic molecules they require. Plants are therefore said to be autotrophic (self-feeding), where as animals are heterotrophic (they eat food). Photosynthesis can be summarised by a simple equation: 6CO2(g) + 6H2O(l) ? C6H12O6(l) + 6O2 The glucose is soluble and turned to insoluble starch for storage, hence we test for starch to show photosynthesis has taken place. From the above equation, we can see the factors that affect photosynthesis: * Light - quantity and quality (colour) * Temperature - needs to be at an optimum for the plant enzymes * CO2 - the amount of (not usually limiting, but in excess) ...read more.


My preliminary work showed that distances of 5, 15, 25, 35, 45, 55, and 65cm from the elodea, gave a good spread of results (distances further away from the elodea were not worth experimenting on, as the elodea photosynthesised at a very slow rate, or not at all. I know this from preliminary series of experiments). Temperature: I will not be heating the water in which I will place the elodea, as this will keep the temperature (fairly) constant. My preliminary experiments showed that using this method, the temperature only varied by 2 or 3?C at the most - and this small amount does not impact the results. CO2: I will be placing the elodea in a test tube filled with a solution of 0.1% Na+HCO3- (and the test tube will be placed in a water bath at a constant temperature). The Na+HCO3- ions will release CO2 for photosynthesis. The CO2 will always be in excess, and my preliminary work showed that this solution worked well, and will not affect the photosynthesising of the elodea. It is by this method that I will control the amount of CO2, keep it constant, and always in excess. Chlorophyll: I will control the amount of chlorophyll, by using the same elodea all the way through my experiment. ...read more.


This test tube will be placed in a beaker, in a water bath. The water will not be heated, so that the temperature will be constant throughout the experiment at room temperature. Room temperature (22-25?C) is also the optimum temperature for the plant enzymes - meaning they will be working at the optimum rate, and will not become denatured, as the temperature will never rise more than 2 or 3?C above the optimum temperature. The test tube will then be fixed in place by a clamp and stand. I will then leave the elodea for a five-minute "settling-in" period, where the elodea will adapt to the conditions. Then, I will place the lamp 5cm away from the elodea, and begin timing. I will be recording the number of O2 bubbles given off by the elodea every minute - this is the rate of photosynthesis. For every distance, I will record the number of O2 given off every minute, and repeat the procedure 3 times. I will then take the average of the 3 readings. This is to be able to accommodate any anomalous results that may crop up. The entire procedure will be repeated at distances of 15, 25, 35, 45, 55, and 65cm. These distances should provide me with sufficient readings for a suitable graph in my analysis. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Green Plants as Organisms section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Green Plants as Organisms essays

  1. Mangrove Soil Analysis

    This is in accordance with the low pH of the Trinity Beach Sample. Conclusion: Bacteria and fungi growth is predominatly determined by the pH levels of the soil. Summary: Different soil types have individual characteristics which in turn affect the vegetation growth in that particular soil.

  2. Investigating the effect of temperature on the rate of photosynthesis

    When GP cannot be made the Calvin cycle cannot be completed, therefore the dark stage of photosynthesis cannot occur, releasing less and less oxygen. My graphs for both my group and the class average generally follow this pattern; therefore I correctly predicted the effect of temperature on the rate of photosynthesis.

  1. Experiment to Investigate the Effect of Temperature on the Rate of Photosynthesis in Elodea.

    * Light wavelength - An action spectrum is the rate of a physiological activity plotted against wavelength of light. In 1881, the German plant physiologist T. W. Engelmann placed a filamentous green alga under the microscope and illuminated it with a tiny spectrum of visible light.

  2. Investigating the effect of Light Intensity on Elodea.

    Looking at graph 1, it is obvious that when the distance of the lamp from the Elodea is at its shortest length (5cm), the average number of bubbles is 64 bubbles per min with a light intensity of 0.04 lux.

  1. Investigation To Find The Effect Of Temperature On The Rate Of Photosynthesis Of Elodea.

    The light color can be fixed by using the same lamp throughout the experiment. Carbon Dioxide- CO2 concentration can affect the rate of photosynthesis since the more CO2 in the air, the more CO2 that can diffuse into the leaf.

  2. An Investigation into Species Diversity with distance along a Pingo.

    As they do so they have more energy, which makes it easier for the bonds in the water molecules to be broken, and the reaction occurs at a faster rate. As the temperature of the habitat continues to rise so does the enzyme activity, however this does not go on indefinitely.

  1. The effects of organic effluent from the seweage on the biodiversty in a freshwater ...

    This prevents photosynthesis which makes oxygen. * Use an oxygen meter to measure the oxygen concentration f the second sample and the difference is a a standard measure of BOD. 10. The results obtained will be used to determine if high BOD in organic effluent rich stream area is the reason for the difference in biodiversty(low)

  2. How temperature affects the rate of photosynthesis.

    A moving substance always has kinetic energy and temperature can be responsible for an increase or decrease in kinetic energy. At a low temperature, an enzyme and a substrate molecule will have a low kinetic energy and will be moving slowly.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work