• 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 whether the intensity of light would affect the rate of photosynthesis in a plant. You will know whether or not it does by counting the number of bubbles.

Extracts from this document...


Katie Garford Background Information Photosynthesis is the process where plants produce their own food. They are self-sufficient. Plants change carbon dioxide and water to make glucose and oxygen. This does not happen without light energy and chlorophyll. Without light energy and chlorophyll carbonic acid would be produced. Light provides the energy for photosynthesis to happen and chlorophyll is an enzyme which speeds up the reaction. Oxygen is a bi-product of photosynthesis and is released into the atmosphere. Glucose is used for biomass and energy or it can be stored as starch. The equation for photosynthesis is: light energy carbon dioxide + water glucose + oxygen. chlorophyll 6CO2 + 6H20 C6H1206 + 602 The temperature, intensity of the light, water supply and carbon dioxide supply all have an effect on how efficiently plants convert the raw materials into the food that they need. To prove that chlorophyll was required for photosynthesis I did two experiments. First of all I tested variegated leaves for starch. When you put iodine on the leaf, the white areas will contain no chlorophyll whereas everywhere else will. You could also put one plant in darkness for 12 hours and another one in light for 12 hours. After that time you test for starch using iodine and the leaf in the dark would turn yellow as it wouldn't contain starch because it hadn't photosynthesised. ...read more.


Prediction I predict that the more intense the light, the higher the rate of photosynthesis. I think this because plants rely on light for photosynthesis and so therefore if the light is not very intense not so many bubbles of oxygen will be produced. As the light is moved away the intensity of the light is reduced and the number of bubbles will decrease steadily. For example, at 25cm away the number of bubbles may be 25 so you would expect the number of bubbles at 50cm away to be 50cm as the light intensity is decreased. I think that no bubbles or very few will be produced at 100cm away from the light. I think the same results will follow for the strength of light. As the strength of light decreases the amount of bubbles will also decrease. Results These results are from the first set of experiments. Voltage(W) 100 100 100 100 100 Distance(cm) 0 25 50 75 100 Bubbles/min. 17 12 7 5 4 Voltage(W) 60 60 60 60 60 Distance(cm) 0 25 50 75 100 Bubbles/min. 17 6 5 3 1 Voltage(W) 40 40 40 40 40 Distance(cm) 0 25 50 75 100 Bubbles/min. 12 3 0 0 0 These results are from the repeat experiment. Voltage(W) 100 100 100 100 100 Distance(cm) 0 25 50 75 100 Bubbles/min. ...read more.


Perfect results could never be achieved as living things do not work at a constant rate. For more accuracy the results could be taken over a period of time, say 4 weeks. This way you would achieve results from when the pondweed is working at different rates. The method used for measuring the number of bubbles wasn't very accurate as counting bubbles can get very boring and miscounting could be a common mistake made and could easily explain anomalous results. Another reason why anomalous data may have been collected is the possibility that the piece of pondweed was damaged. It may have got too hot which would have denatured the chlorophyll and this would affect the rate of photosynthesis as chlorophyll is required for photosynthesis to occur. To overcome this problem you could change the piece of pondweed after each set of results was taken or you could leave a set amount of time after each set of results was collected for the pondweed to cool down. If I was to do this experiment in the future then I would use different light filters to change the colour of the light. By doing this I would find out if the plant prefers to absorb certain colours over others. For example, does chlorophyll prefer green as it is green itself. To do this I would use the same set up as I did for this experiment but the distance and light voltage would stay the same whereas the light filters would change in order to get different colours. ...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. Photosynthesis. The aim of my experiment was to determine whether or not the intensity ...

    This was because photosynthesis is a reaction, which needs energy from light to work, so as the amount of energy available from light increased with the rise in light intensity, so did the amount of oxygen produced as a product of photosynthesis.

  2. How does light intensity affect the rate of photosynthesis

    Evaluation: My experiment went well in general and once I had settled on a suitable method everything went according to plan. As I started my experiment with the above mentioned method, I found it difficult to create the proper situation where I could carry out a fair and effective experiment and record my results accurately.

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

    This occurs because molecules are moving more quickly and there is a greater chance of a collision resulting in a chemical reaction. At some point, a temperature is reached that is an optimum temperature. The photosynthetic reaction rate is at its quickest rate at this point.

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

    This is not a very accurate way to keep the temperature level. The temperature in the electronic water baths, were sometimes not on the temperature programmed, therefore we had to change it with ice and warm water also. Sodium carbonate was added to speed up the rate of photosynthesis; the amount of this however was not measured.

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

    The end of the plant should be cut at an angle, in order to release CO2 most effectively. The thermometer monitors the temperature of the water bath, thus checking whether or not there is a temperature increase or decrease, resulting in the change in the rate of p/s in the Elodea specimen.

  2. Investigating the effect of Light Intensity on Elodea.

    The method used was suitable in finding relationships between distances and support my prediction, however not accurate enough to produce results that can prove my prediction, or support a firm conclusion. The data produced gave a few anomalous results on graph 1, at distance 20cm and on graph 2 at distance cm.

  1. Investigate the effect of light intensity on the rate of photosynthesis in an aquatic ...

    I will measure the amount of oxygen produced by counting the number of bubbles of oxygen given off by the pond weed within a set time of 3 minutes. I could have measured the amount of oxygen given off by the pond weed another way though, by measuring the volume

  2. How temperature affects the rate of photosynthesis.

    This should be done to make sure that the temperature is the one needed before inserting the elodea and also it remains constant throughout. Change the temperature as and when needed. 18. Convert the length calculated to volume using the formula - ?r2l where l is 0.8mm and note down the result.

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