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

The aim of the experiment is to determine what effect light intensity has upon the rate of photosynthesis of Canadian Pondweed (Elodea).

Extracts from this document...


Claire Shaftoe 10JTe Biology Assessed Practical Introduction- Photosynthesis is the chemical process, which takes place in every green plant to produce food in the form of glucose. Plants use the suns energy to join together water and carbon molecules to make the glucose, which is sent around the plant to be used in respiration. 6CO + 6H O ? C H O + 12O (in the presence of light energy and chlorophyll) Aim- The aim of the experiment is to determine what effect light intensity has upon the rate of photosynthesis of Canadian Pondweed (Elodea). Prediction- I think that as the light intensity increases, the rate of photosynthesis will as well. This is because plants need light energy to photosynthesise, to join water and carbon molecules together to form glucose. If more light energy is available to the plant, then it will be able to photosynthesise at a faster rate. The light provides energy for the reaction to take place, and so if a plant has more light then it should have more energy to use in the reactions, and the rate of reaction should become faster. After a certain point, the rate of reaction will stop increasing and become constant. This will either be because another factor (such as Carbon Dioxide or temperature) ...read more.


* The amount of water must be kept the same because water is needed for the reactions to occur in a plant, and so if there is a lack of water, then reactions will be slower, if they take place at all. Another reason that the amount of water must be kept the same is because when plants do not have enough water, they close the stomata, to prevent further water loss. However, when the stomata are closed, carbon dioxide cannot diffuse into the leaf, which would also slow down the rate of photosynthesis. * Temperature must remain constant because enzymes are used in photosynthesis and the respiration of the plant. Therefore, as the temperature increases so will the rate of reaction of the enzymes, up to a certain point, where the enzymes will be denatured. The temperature could be kept constant by performing the experiment in one session, so that the air temperature should not change enough to affect the water temperature. * The type of plant should be kept the same because different plants have different rates of photosynthesis due to different leaf structures. Even plants of the same species can have slightly different rates of photosynthesis, because there may be more or less chlorophyll in the leaves to absorb light. ...read more.


I repeated these results until I was satisfied that the sizes of the bubbles were the same, or very similar to the rest of the results that I had collected. In a future experiment, a more accurate way of measuring the amount of gas given off would be to measure the volume of gas produced, rather than just counting the bubbles. I would do this by having a scale on the test tube, where the gas collects. Then I could measure how much the water level drops by, or how much more gas there is at the end of the minute than there was at the beginning of the experiment. Another problem was that there were air bubbles trapped in the funnel and on the test tube, from when I had set the equipment up. I tried to release all of the bubbles before the experiment started, but this was not very easy and so some remained, mainly on the edge of the test tube. Although I am almost certain that the bubbles that I counted were from the plant as a result of photosynthesis, it is possible that one or two were the air bubbles that had been there since the beginning. A way to get rid of the bubbles on the test tube could be to use a stirring rod, or something similar to knock them off the edge, so that they rose to the top. ...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. Marked by a teacher

    Investigate the relationship between wavelength of light and the rate of photosynthesis using pondweed.

    3 star(s)

    11. A 30cm by 30cm square piece of paper to reflect back any light to the Canadian pondweed, to make sure the maximum amount of photosynthesis can take place, by using the light source to its full potential. This will scatter the light back on to the test tube, which is

  2. Photosynthesis. The aim of my experiment was to determine whether or not the intensity ...

    These factors do not immediately limit the rate of photosynthesis, but rather gradually. As light intensity increases further, so the rate of photosynthesis is being limited by other factors more and more, until the rate of photosynthesis is constant, and so is almost certainly limited in full by another factor.

  1. Investigating the effect of Light Intensity on Elodea.

    26 26 60 17 18 16 17 From this we can see that there is a definite correlation. As the distance from the plant increases the number of bubbles decreases. For my final experiment I intend to record results from the following distances: 50, 45, 40, 35, 30, 25, 20, 15, 10, 5.

  2. The aim of my experiment is to find out how light intensity affects the ...

    4. I than set the pondweed in the funnel 5. And covered the top of the funnel with boiling tube so the oxygen in the air would not affect my experiment. 6. I added a small amount of Sodium Hydrogen Carbonate (3g)

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

    At a certain point of enzyme concentration, the reaction will not get faster, even if more enzyme is added, because all the substrate molecules will be bound to the active sites of enzymes. The graph to show the effect of varying enzyme concentration on an enzyme controlled reaction is as follows: (Cambridge Biology 1)

  2. To investigate the effect of light intensity on the rate of photosynthesis on elodea ...

    I also chose to take the reading from an increasing distance by 10cms. This was because I thought that it would not be necessary to do them at 5cm interval because if we did 3 results for each 10cm interval then the average of this would be more accurate.

  1. The aim of this experiment is to investigate the factors affecting photosynthesis in Elodea.

    to this point, because light is needed for photosynthesis, and if you increase the intensity then more energy is being supplied to the cells every second, which is then used to convert carbon dioxide and water into glucose and oxygen.

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

    The rate of photosynthesis is measured by oxygen released. However in our preliminary we did this by counting bubbles. However this is also inaccurate as bubbles are all of different sizes, therefore volume is not measured accurately. In our actual experiment we will use a scale. This measures the volume of the bubbles, therefore will be more accurate to measure rate.

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